Ribbon Communications Inc. (RBBN)

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with our financial statements and the related notes included in Item 8, “Financial Statements and Supplementary Data” in this Annual Report on Form 10-K. This discussion contains forward-looking statements that reflect our plans, estimates and beliefs and involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of various factors including, but not limited to, those disclosed in Item 1A, “Risk Factors”, elsewhere in this Annual Report on Form 10-K, in other documents filed with the SEC and otherwise publicly disclosed. Please refer to “Cautionary Note Regarding Forward-Looking Statements” above for additional information. For a complete description of our business and other important information, please refer to Item 1 of Part I of this Annual Report on Form 10-K.

Overview

We are a leading global provider of communications technology to service providers and enterprises. We provide a broad range of software and high-performance hardware products, network solutions, and services that enable the secure delivery of data and voice communications, and high-bandwidth networking and connectivity for residential consumers and for small, medium, and large enterprises and industry verticals such as finance, education, government, utilities, and transportation. Our mission is to create a recognized global technology leader providing cloud-centric solutions that enable the secure exchange of information, with unparalleled scale, performance and elasticity. We are headquartered in Plano, Texas, and have a global presence with research and development or sales and support locations in over thirty countries around the world.

Key Trends and Economic Factors Affecting Ribbon

Supplier Disruptions. Ongoing uncertainty in the global economy due to inflation, the wars in Israel and Ukraine, national security concerns and other factors, continue to disrupt various manufacturing, commodity and financial markets, increase volatility, and impede global supply chains. Our ability to deliver our solutions as agreed upon with our customers depends in part on the ability of our global contract manufacturers, vendors, licensors and other business partners to deliver products or perform services we have procured from them.

Continued uncertain global economic conditions may cause our customers to restrict spending or delay purchases for an indeterminate period of time and consequently cause our revenues to decline. Further, such factors may negatively impact our operating costs resulting in a reduction in net income. The degree to which the ongoing wars in Israel and Ukraine and the inflationary and high interest rate environment impacts our future business, financial position and results of operations will depend on developments beyond our control.

The Ongoing Wars in Israel and Ukraine. The uncertainty resulting from the wars in Israel and Ukraine, and the threat for expansion of one or both of these wars, could result in some of our customers delaying purchases from us. Further, a number of our employees in Israel are members of the military reserves and subject to immediate call-up in response to the war in Israel. Following the terrorist attacks in Israel in October 2023, a number of our employees have been activated for military duty and we expect that additional employees will also be activated if the war in Israel continues. While we have business continuity plans in place to address the military call-ups, it could affect the timing of projects in the short-term as the work is shifted to other team members both inside and outside of Israel.

The U.S. and other European countries have imposed sanctions and trade restrictions against Russia in connection with the war in Ukraine. These sanctions and restrictions currently prohibit our ability to sell hardware products in Russia or provide any replacement parts in Russia. The sanctions continue to evolve and further changes in the current sanctions or trade restrictions could further limit our ability to sell products and services to customers in Russia, our ability to collect on outstanding accounts receivable from such customers, and our ability to repatriate funds. If we are further limited in our ability to sell products and services to Russia and other countries for an extended period, it could have a material impact on our financial results.

Inflation and Interest Rates. We continue to see near-term impacts on our business due to inflation, including ongoing global price pressures resulting in higher energy prices, component costs, freight premiums, and other operating costs above normal rates. Although headline inflation in the United States and Europe appears to be easing, core inflation (excluding food and energy prices) remains elevated and is a source of continued cost pressure on businesses and households. Interest rates remain high as central banks in developed countries attempt to subdue inflation while government deficits and debt remain at

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high levels in many global markets. However, since its peak in 2024, the Federal Reserve lowered the federal funds interest rate to 4.48% in December 2024, as a result of its view that inflation is cooling. Yet, the economic outlook remains uncertain, and the implications of current and future tariffs, higher government deficits and debt, tighter monetary policy, and potentially higher long-term interest rates may drive a higher cost of capital for our business.

Presentation

Unless otherwise noted, all financial amounts, excluding tabular information, in this Management’s Discussion and Analysis of Financial Condition and Results of Operations (“MD&A”) are rounded to the nearest million dollar amount, and all percentages, excluding tabular information, are rounded to the nearest percentage point.

Private Placement

On March 28, 2023, we issued 55,000 shares of newly designated Series A Preferred Stock (the “Preferred Stock”) to investors in a private placement offering at a price of $970 per share, along with 4.9 million warrants (the “Warrants”) to purchase shares of our common stock, par value $0.0001 per share (the “Private Placement”), at an exercise price of $3.77 per share. The proceeds from the Private Placement were approximately $53.4 million, including approximately $10 million from existing related party stockholders. On June 25, 2024, we redeemed the Preferred Stock with a portion of the proceeds from the refinancing of the 2020 Credit Facility at a rate of 103% for a total of approximately $63.5 million. The Warrants remain outstanding and without modification. For additional detail on the Private Placement, see Note 16 - Preferred Stock and Warrants to our consolidated financial statements.

Operating Segments

Our CODM assesses our performance based on the performance of two separate organizations within Ribbon, the Cloud and Edge operating segment (“Cloud and Edge”) and the IP Optical Networks operating segment (“IP Optical Networks”). For additional details regarding our operating segments, see Note 18 - Operating Segment Information to our consolidated financial statements.

Financial Overview

Financial Results

We reported income from operations of $16.9 million for 2024 and a loss from operations of $24.3 million for 2023. We reported a net loss of $54.2 million for 2024 and $66.2 million for 2023.

Our revenue was $833.9 million in 2024, comprised of $505.2 million attributable to Cloud and Edge and $328.7 million attributable to IP Optical Networks. Our revenue was $826.3 million in 2023, comprised of $477.6 million attributable to Cloud and Edge and $348.7 million attributable to IP Optical Networks. Our gross profit was $439.5 million in 2024, comprised of $329.2 million attributable to Cloud and Edge and $110.3 million attributable to IP Optical Networks. Our gross profit was $408.1 million in 2023, comprised of $300.0 million attributable to Cloud and Edge and $108.1 million attributable to IP Optical Networks. Our gross margin was 52.7% in 2024 and 49.4% in 2023. In 2024, our Cloud and Edge gross margin was 65.2% and our IP Optical Networks gross margin was 33.6%. In 2023, our Cloud and Edge gross margin was 62.8% and our IP Optical Networks gross margin was 31.0%. The higher revenue in 2024 compared to 2023 is due to $27.6 million of higher Cloud and Edge sales, primarily to U.S. service providers and Federal agencies, partially offset by $20.0 million of lower IP Optical Networks sales led by lower sales into Eastern Europe and India, which were partially offset by growth in the U.S. rural market.

Our operating expenses were $422.6 million in 2024 and $432.4 million in 2023. Our 2024 operating expenses included $26.0 million of amortization of acquired intangible assets, and $10.2 million of restructuring and related expense. Our 2023 operating expenses included $28.6 million of amortization of acquired intangible assets, $4.5 million of acquisition-, disposal- and integration-related expense, and $16.2 million of restructuring and related expense.

We recorded stock-based compensation expense of $16.1 million in 2024 and $21.8 million in 2023. These amounts are included as components of both Cost of revenue and Operating expenses in our consolidated statements of operations.

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See “Results of Operations” in this MD&A for additional discussion of our results of operations for the years ended December 31, 2024 and 2023.

Restructuring and Cost Reduction Initiatives

Our President and CEO approved workforce reductions in 2024 for certain of our operating locations to correspond with the current sales levels in those areas. We recorded $2.1 million in 2024 related to these actions.

In February 2023, our Board of Directors approved a strategic restructuring program (the “2023 Restructuring Plan”) to streamline our operations in order to support our investment in critical growth areas. The 2023 Restructuring Plan includes, among other things, charges related to a workforce reduction. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2023 Restructuring Plan, we recorded restructuring and related expense for severance related costs of $2.0 million and $9.9 million in 2024 and 2023, respectively. We anticipate that we will record nominal future expense for severance in connection with the 2023 Restructuring Plan.

In February 2022, our Board of Directors approved a strategic restructuring program (the “2022 Restructuring Plan”) to streamline our operations in order to support our investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2022 Restructuring Plan, we recorded restructuring and related expense of $6.1 million in 2024 for variable and other facilities-related costs. In 2023, we recorded $6.3 million of expense for the 2022 Restructuring Plan, comprised of $5.3 million for variable and other facilities-related costs, and $1.0 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease. In 2022, we recorded $10.2 million of expense for the 2022 Restructuring Plan, comprised of $3.3 million for variable and other facilities-related costs, $1.6 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease, and $5.3 million for severance and related costs. We anticipate that we will expense $5 million in 2025 related to the 2022 Restructuring Plan.

For facilities that are part of a restructuring plan, and for which we have no intent or ability to enter into a sublease, we recognize accelerated rent amortization over the period from the date that we commence the plan to fully or partially vacate a facility through the final vacate date. We did not record accelerated rent amortization in 2024. We recorded $1.0 million and $1.6 million for accelerated rent amortization in the years ended December 31, 2023 and 2022, respectively. We continue to evaluate our properties included in our restructuring plans for accelerated amortization and/or right-of-use asset impairment. We may incur additional expense in the future if we are unable to sublease other locations included in these initiatives.

Critical Accounting Policies and Estimates

This MD&A is based upon our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosure of contingent assets and liabilities. We base our estimates and judgments on historical experience, knowledge of current conditions and beliefs of what could occur in the future given available information. We consider the following accounting policies to be both those most important to the portrayal of our financial condition and those that require the most subjective judgment. The significant accounting policies that we believe are the most critical include revenue recognition, the valuation of inventory, debentures and warrants received as sale consideration, warranty accruals, loss contingencies and reserves, stock-based compensation, the Preferred Stock and Warrants, business combinations, goodwill and intangible assets, accounting for leases, and accounting for income taxes. If actual results differ significantly from management’s estimates and projections, there could be a material effect on our consolidated financial statements.

Revenue Recognition. We derive revenue from two primary sources: products and services. Product revenue is generated from sales of our stand-alone software, as well as our proprietary hardware and software that function together to deliver the products’ essential functionality. Both software and hardware are also sold on a standalone basis. Services include customer support (software updates and technical support), consulting, design services, installation services and training. A typical contract includes both product and services. Generally, contracts with customers contain multiple performance obligations. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to the separate performance obligations on a relative standalone selling price (“SSP”) basis.

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The software licenses typically provide a perpetual right to use our software. However, we also sell term-based software licenses that expire and Software-as-as-Service (“SaaS”)-based software, which are referred to as subscription arrangements. We do not customize our software nor are installation services required, as the customer has a right to utilize internal resources or a third-party service company. The software and hardware are delivered before related services are provided and are functional without professional services or customer support. We have concluded that our software licenses are functional intellectual property that are distinct, as the user can benefit from the software on its own. The product revenue related to our perpetual licenses is typically recognized when the software is made available for download, as this is the point that the user of the software can direct the use of and obtain substantially all of the remaining benefits from the functional intellectual property. The product revenue related to our term-based software licenses is recognized over the license period. We begin to recognize revenue related to the renewal of term-based software licenses at the start of the renewal period. Revenue related to our SaaS-based software is recognized ratably over the service period as the customer does not take possession of the software or have the ability to take possession of the software.

Service revenue includes revenue from customer support and other professional services. We offer warranties on our products. Certain of our warranties are considered to be assurance-type in nature, ensuring that the product is functioning as intended. Assurance-type warranties do not represent separate performance obligations. We also sell separately-priced maintenance service contracts which qualify as service-type warranties and represent separate performance obligations. We do not allow and have no history of accepting product returns.

Customer support includes software updates on a when-and-if-available basis, telephone support, integrated web-based support and bug fixes or patches. We sell our customer support contracts at a percentage of list or net product price related to the support. Customer support revenue is recognized ratably over the term of the customer support agreement, which is typically one year.

Our professional services include consulting, technical support, resident engineer services, design services and installation services. Because control transfers over time, revenue is recognized based on progress toward completion of the performance obligation. The method to measure progress toward completion requires judgment and is based on the nature of the products or services to be provided.

We generally use the input method to measure progress for our contracts and to recognize revenue because we believe this method, in general, best depicts the transfer of assets to the customer. The input method measures costs we have incurred in the period for the contracts. In some infrequent instances, we may engage a third-party to perform services for us and in those cases, we use the output method to recognize revenue because it best depicts the transfer of assets to the customer. Under the output method, there is a cost-to-cost measure of progress. The progress toward completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. When the measure of progress is based upon expended labor, progress toward completion is measured as the ratio of labor time expended to date versus the total estimated labor time required to complete the performance obligation. Revenue is recorded proportionally as costs are incurred or as labor is expended. Costs to fulfill these obligations can include internal labor as well as subcontractor costs.

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We offer customer training courses, for which the related revenue is typically recognized over the period the training services are performed, typically over one to five days.

Our contracts with customers often include promises to transfer multiple products and services to the customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment.

Judgment is required to determine the SSP for each distinct performance obligation. SSPs are typically estimated using observable historical transactions of our products and services sold in comparable circumstances to similar customers, including when products and services are sold on a standalone basis. We use a range of amounts to estimate SSP when we sell each of the products and services separately and need to determine whether there is a discount to be allocated based on the relative SSP of the various products and services.

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In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions, current pricing practices, product specific business objectives, the cost to provide the performance obligation, and other observable inputs. We typically have more than one SSP

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for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information such as the size of the customer and geographic region in determining the SSP. As our go-to-market strategies evolve, we may modify our pricing practices in the future, which could result in changes to SSP. However, historically, we have not had any material changes to our SSP, nor do we expect any material changes to our SSP estimates in the future.

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Valuation of Inventory. We review inventory for both potential obsolescence and potential loss of value periodically. In this review, we make assumptions about the future demand for and market value of the inventory and, based on these assumptions, estimate the amount of any excess, obsolete or slow-moving inventory.

We write down our inventories if they are considered to be obsolete or at levels in excess of forecasted demand. In these cases, inventory is written down to estimated realizable value based on historical usage and expected demand. Inherent in our estimates of market value in determining inventory valuation are estimates related to economic trends, future demand for our products and technical obsolescence of our products. If future demand or market conditions are less favorable than our projections, additional inventory write-downs could be required and would be reflected in the cost of revenue in the period the revision is made. To date, we have not been required to revise any of our assumptions or estimates used in determining our inventory valuations.

We write down our evaluation equipment at the time of shipment to our customers, as it is not probable that the inventory value will be realizable.

Investments. We received debentures (the “Debentures”) and warrants (the “AVCT Warrants”) as sale consideration in connection with our December 1, 2020 sale of the Kandy Communications Business to American Virtual Cloud Technologies, Inc. (“AVCT”) (the “Kandy Sale”). On September 8, 2021 (the “Debenture Conversion Date”), the Debentures were converted into shares of AVCT common stock (the “Debenture Shares”). In connection with the conversion of the Debentures to the Debenture Shares, we elected to use the fair value option to account for its equity investment in AVCT as permitted under Accounting Standards Codification (“ASC”) 825, Financial Instruments (“ASC 825”), which then refers to ASC 820, Fair Value Measurement (“ASC 820”) to provide the fair value framework for valuing such investments. In accordance with ASC 820, we recorded the investment in AVCT at fair value, with changes in fair value recorded as a component of Other (expense) income, net, in the consolidated statements of operations.

On August 29, 2022, we and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of our investment in the Debenture Shares and the AVCT Warrants. Pursuant to the settlement agreement, we also entered into a Wind Down Agreement with AVCT, pursuant to which a Reseller Agreement between the parties, as previously amended, was terminated, and we were granted a non-exclusive perpetual license to use and modify certain intellectual property owned by AVCT comprising WebRTC gateway technology that is integrated with Ribbon’s SBCs and Application Servers. The perpetual license granted by AVCT is classified as Intangible assets, net in our consolidated balance sheets.

Warranty Accruals. We record warranty liabilities for estimated costs of fulfilling our obligations under standard limited hardware and software warranties at the time of sale. The liability for standard warranties is included in Accrued expenses and other and Other long-term liabilities in our consolidated balance sheet. The specific warranty terms and conditions vary depending upon the country in which we do business, but generally include material costs, technical support, labor and associated overhead over a period ranging from one to three years. We provide for the estimated costs to fulfill customer warranty obligations for certain of our products upon recognition of the related revenue. Warranty is included as a component of Cost of revenue in our consolidated statements of operations, and is determined based on actual warranty cost experience, estimates of component failure rates and our management’s industry experience. Our sales contracts do not permit the right of return of the product by the customer after the product has been accepted.

Loss Contingencies and Reserves. We are subject to ongoing business risks arising in the ordinary course of business that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. We regularly evaluate current information available to determine whether such amounts should be adjusted and record changes in estimates in the period they become known. We are subject to various legal claims. We reserve for legal contingencies and legal fees when the amounts are probable and reasonably estimable.

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Stock-Based Compensation. Our stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which is generally the vesting period.

We use the Black-Scholes valuation model for estimating the fair value on the date of grant of employee stock options. Determining the fair value of stock option awards at the grant date requires judgment regarding certain valuation assumptions, including the volatility of our stock price, expected term of the option, risk-free interest rate and expected dividends. Changes in such assumptions and estimates could result in different fair values and could therefore impact our earnings. Such changes, however, would not impact our cash flows. The fair value of restricted stock awards, restricted stock units and performance-based awards is based upon our stock price on the grant date.

We grant performance-based stock units, some of which include a market condition, to certain of our executives and certain other employees. We use a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity, and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values. We are required to record expense through the respective final vesting dates regardless of the number of shares that are ultimately earned. Once the grant date criteria have been met for a fiscal year performance period, we record stock-based compensation expense based on our assessment of the probability that the respective performance condition will be achieved and the level, if any, of such achievement. The Compensation Committee determines the number of shares earned, if any, after our financial results for each fiscal year performance period are finalized. Upon determination by the Compensation Committee of the number of shares that will be received upon vesting, such number of shares becomes fixed and the unamortized expense is recorded through the remainder of the service period, at which time any performance-based stock units earned will vest pending each employee’s continuing employment with us through that date.

The amount of stock-based compensation expense recorded in any period for unvested awards requires estimates of the amount of stock-based awards that are expected to be forfeited prior to vesting, as well as assumptions regarding the probability that performance-based stock awards without market conditions will be earned.

Preferred Stock and Warrants. We accounted for the Preferred Stock until it was redeemed on June 25, 2024 and we continue to account for the Warrants as liability-classified instruments based on an assessment of their specific terms in accordance with ASC Topic 480, Distinguishing Liabilities from Equity. The fair value option was elected for the Preferred Stock, as we considered fair value to best reflect its expected future economic value. These liabilities are remeasured to fair value at each reporting date using the same valuation methodology applied upon issuance using current input assumptions. The Preferred Stock was considered to be debt for our Consolidated Net Leverage Ratio covenant calculation required under our 2020 Credit Facility.

Business Combinations. We allocate the purchase price of acquired companies to identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. Significant management judgments and assumptions are required in determining the fair value of assets acquired and liabilities assumed, particularly acquired intangible assets which are principally based upon estimates of the future performance and cash flows expected from the acquired business and applied discount rates. While we use our best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at a business combination date, our estimates and assumptions are inherently uncertain and subject to refinement. If different assumptions are used, it could materially impact the purchase price allocation and our financial position and results of operations. Any adjustments to assets acquired or liabilities assumed subsequent to the purchase price allocation period are included in operating results in the period in which the adjustments are determined. Intangible assets typically are comprised of in-process research and development, developed technology, customer relationships, trade names and internal use software.

Goodwill and Intangible Assets. Goodwill is not amortized, but instead is tested for impairment annually, or more frequently if indicators of potential impairment exist. Intangible assets with estimated lives and other long-lived assets are reviewed for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by comparing the carrying amount of the asset to future net undiscounted pretax cash flows expected to be generated by the asset. If these comparisons indicate that an asset is not recoverable, we will recognize an impairment loss for the amount by which the carrying value of the asset exceeds the related estimated fair value.

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We perform a fair value analysis for each reporting unit using both an income and market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. We assess each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately. Any impairment charges are reported separately in our consolidated statements of operations.

Judgment is required in determining whether an event has occurred that may impair the value of goodwill, identifiable intangible assets or other long-lived assets. Factors that could indicate an impairment may exist include significant underperformance relative to plan or long-term projections, strategic changes in business strategy, significant negative industry or economic trends, a significant change in circumstances relative to a large customer, a significant decline in our stock price for a sustained period and a decline in our market capitalization to below net book value. We must make assumptions about future control premiums, market comparables, cash flows, operating plans, discount rates and other factors to determine recoverability.

Our annual testing for impairment of goodwill is completed as of October 1. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may be either an operating segment or a portion of an operating segment. Our reporting units are our two operating segments, Cloud and Edge and IP Optical Networks. For our annual impairment testing, we perform a fair value analysis using both an Income and Market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. We assess each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately.

Based upon the completion of our 2024, 2023, and 2022 annual tests for goodwill impairment, we determined that there was no impairment of goodwill for either of our reporting units.

Leases. We account for our leases in accordance with Accounting Standards Codification (“ASC”) 842, Leases (“ASC 842”). We have operating leases for corporate offices, and research and development facilities and historically had finance leases for certain equipment. Operating leases are reported separately in our consolidated balance sheets. Assets acquired under finance leases, if any, are included in Property and equipment, net, in the consolidated balance sheets.

We determine if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides us with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, we do not separate lease and non-lease components but rather, account for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term.

For operating leases, lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases includes both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. We expense all variable lease costs as incurred.

Accounting for Income Taxes. Our provision for income taxes is comprised of both current taxes and deferred taxes. The current income tax provision is generally calculated as the estimated taxes payable or refundable on tax returns to be filed for the year ended December 31, 2024. We provide for deferred income taxes based on temporary differences between financial and taxable income, net operating loss carryforwards, tax credit carryforwards and any required valuation allowances.

We assess the recoverability of all deferred tax assets recorded on the balance sheet and provide any necessary valuation allowances as required. In evaluating our ability to realize our deferred tax assets, we consider all available positive and negative evidence, including our past operating results, the existence of cumulative income in the most recent years, changes in our business operations, and our forecast of future taxable income. In determining future taxable income, we make assumptions, including the amount of state, federal and international pre-tax income, the reversal of temporary differences and the implementation of feasible and prudent tax planning strategies. These assumptions require significant judgment about the forecasts of future taxable income and are consistent with the plans and estimates we are using to manage our underlying businesses. Such assessment is completed on a jurisdiction-by-jurisdiction basis.

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We have provided for income taxes on the undistributed earnings of our non-U.S. subsidiaries as of December 31, 2024, excluding Ireland and Israel, which are indefinitely reinvested. Accordingly, we are required to recognize deferred taxes for 2024 on the outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings.

We assess all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and we determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of recognized tax benefit is still appropriate. The recognition and measurement of tax benefits require significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Results of Operations

Years Ended December 31, 2024 and 2023

Revenue. Revenue for the years ended December 31, 2024 and 2023 was as follows (in thousands, except percentages):

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Segment revenue for the years ended December 31, 2024 and 2023 was as follows (in thousands):

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The increase in our product revenue in 2024 compared to 2023 was primarily the result of $26 million of higher sales of our Cloud and Edge products, partially offset by $24 million of lower sales of our IP Optical products. The increase in revenue from the sale of Cloud and Edge products was primarily attributable to sales into U.S. service providers, U.S. Federal agencies and global enterprise customers. The decrease in revenue from the sale of IP Optical products was primarily attributable to lower sales in Eastern Europe and India.

Revenue from sales to enterprise customers was 39% and 32% of our product revenue in 2024 and 2023, respectively. These sales were made through both our direct sales team and indirect sales channel partners. The increase in enterprise sales reflects stronger sales of our products to customers in Federal agencies.

Revenue from indirect sales through our channel partner program was 38% and 35% of our product revenue in 2024 and 2023, respectively. The increase in channel sales in 2024 reflects stronger IP Optical Networks deployments through systems integrators as well as sell-thru service provider channel partners in Eastern Europe.

The timing of the completion of customer projects and revenue recognition criteria satisfaction may cause our product revenue to fluctuate from one period to the next.

Service revenue is primarily comprised of software and hardware maintenance and support (“maintenance revenue”) and network design, installation and other professional services (“professional services revenue”).

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Service revenue for the years ended December 31, 2024 and 2023 was comprised of the following (in thousands, except percentages):

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Segment service revenue for the years ended December 31, 2024 and 2023 was comprised of the following (in thousands):

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Total service revenue was $5 million higher in 2024 compared to 2023 due to increased revenue in both of our segments. Total service revenue increased by $4 million and $1 million in our IP Optical Networks and Cloud and Edge segments, respectively.

Maintenance revenue was $5 million lower in 2024 compared to 2023 primarily due to modestly lower renewal rates from decommissioning some older legacy equipment with several Cloud and Edge customers.

Professional services revenue was $10 million higher in 2024 compared to 2023, with increases of $8 million and $2 million in our Cloud and Edge and IP Optical Networks segments, respectively. The higher revenue in Cloud and Edge is due to the growth in services to U.S. service providers, primarily for voice modernization projects with Verizon and U.S. Federal agencies. Our IP Optical Networks segment experienced growth in sales of services primarily in the North America and APAC regions.

The following customer contributed 10% or more of our revenue in the years ended December 31, 2024 and 2023:

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Revenue earned from customers domiciled outside the United States was 53% and 58% of total revenue in 2024 and 2023, respectively. U.S. revenue is increasing due to higher sales into the U.S. market from both the Cloud and Edge and IP Optical Networks segments. Due to the timing of project completions, we expect that the domestic and international components as a percentage of our revenue may fluctuate from quarter to quarter and year to year. Our total revenue for the years ended December 31, 2024 and 2023 was disaggregated geographically as follows (in thousands):

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Our deferred product revenue was $14 million at December 31, 2024 and $17 million at December 31, 2023. Our deferred service revenue was $126 million at December 31, 2024 and $116 million at December 31, 2023. Our deferred revenue balance may fluctuate as a result of the timing of revenue recognition, customer payments, maintenance contract renewals, contractual billing rights and maintenance revenue deferrals included in multiple element arrangements.

We expect that our total revenue in 2025 will increase compared to our revenue in 2024 due to the growth in the Cloud & Edge segment, particularly with the increased purchases from Verizon as part of a voice modernization project, as well as growth in IP Optical segment sales. From a regional perspective, we anticipate continued IP Optical revenue growth in 2025 from North America, and EMEA, offset by lower revenue in Eastern Europe due to additional trade restrictions. In the Cloud & Edge segment, we expect continued revenue growth from enterprise customers, as well as higher U.S. service provider spending.

Cost of Revenue/Gross Margin. Our cost of revenue consists primarily of amounts paid to third-party manufacturers for purchased materials and services, royalties, amortization of acquired technology, inventory valuation adjustments, warranty costs, and manufacturing and services personnel and related costs. Our cost of revenue, gross profit and gross margin for the years ended December 31, 2024 and 2023 were as follows (in thousands, except percentages):

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Our segment cost of revenue, gross profit and gross margin for the years ended December 31, 2024 and 2023 were as follows (in thousands, except percentages):

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Our gross margin was 3.3 percentage points higher in 2024 compared to 2023. This increase was the result of higher margins in both of our segments. The higher margin in our IP Optical segment was due to favorable regional mix, partially offset by lower sales volume and higher royalties. The higher margin in our Cloud and Edge segment was primarily attributable to favorable product mix and lower costs associated with an increase in software sales.

We expect our overall consolidated gross margin to decrease slightly in 2025 due to higher expected sales in our IP Optical segment, which has lower margins due to the higher hardware content in its products, as well as the higher mix of professional services revenue in our Cloud and Edge segment which generates lower gross margins than product sales.

Research and Development. Research and development (“R&D”) expenses consist primarily of salaries and related personnel expenses and prototype costs for the design, development, testing and enhancement of our products. R&D expenses for the years ended December 31, 2024 and 2023 were as follows (in thousands, except percentages):

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The decrease in our research and development expenses in 2024 compared to 2023 was primarily attributable to approximately $9 million of lower expenses in our IP Optical Networks segment and approximately $2 million of lower expenses in our Cloud and Edge segment. The reduced expenses are a combination of lower employee headcount and outside subcontractors resulting from the cost savings implemented in the 2023 Restructuring Plan.

Our IP Optical Networks R&D investment is focused on significantly expanding our portfolio of IP Routing solutions, adding additional features and capabilities to our Optical Transport portfolio, and supporting features in our next generation SDN management and orchestration platform.

Some aspects of our R&D efforts require significant short-term expenditures, the timing of which may cause significant variability in our expenses. We believe that rapid technological innovation is critical to our long-term success, and we are tailoring our investments to meet the requirements of our customers and market. We believe that our R&D expenses will increase modestly in 2025 primarily due to higher employee and consulting costs related to modifying certain legacy products and certain of our cloud native solutions.

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Sales and Marketing. Sales and marketing expenses consist primarily of salaries and related personnel costs, commissions, travel and entertainment expenses, promotions, customer trial and evaluations inventory and other marketing and sales support expenses. Sales and marketing expenses for the years ended December 31, 2024 and 2023 were as follows (in thousands, except percentages):

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Sales and marketing expenses in 2024 were relatively flat compared to 2023.

We believe our sales and marketing expenses will be relatively flat in 2025 as compared to 2024.

General and Administrative. General and administrative expenses consist primarily of salaries and related personnel costs for executive and administrative personnel, and audit, legal and other professional fees. General and administrative expenses for the years ended December 31, 2024 and 2023 were as follows (in thousands, except percentages):

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The increase in general and administrative expenses in 2024 compared to 2023 was primarily attributable to a $5.0 million legal settlement and associated legal fees related to certain specific legal matters, as well as increased employee incentive costs.

We believe that our general and administrative expenses in 2025 will decrease compared to our 2024 levels, primarily due to lower litigation expenses, partially offset by higher employee costs related to annual merit increases.

Amortization of Acquired Intangible Assets included in Operating expenses. Amortization of acquired intangible assets included in Operating expenses (“Opex Amortization”) for the years ended December 31, 2024 and 2023 was as follows (in thousands, except percentages):

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Opex Amortization was lower in 2024 compared to 2023 due to our method of amortization. We record our amortization in relation to expected future cash flows rather than on a straight-line basis. Accordingly, such expense may vary from one period to the next.

Acquisition-, Disposal- and Integration-Related. Acquisition-, disposal- and integration-related expenses include those expenses related to acquisitions that we would otherwise not have incurred. Acquisition- and disposal-related expenses include professional and services fees, such as legal, audit, consulting, paying agent and other fees. Integration-related expenses represent incremental costs related to combining our systems and processes with those of acquired businesses, such as third-party consulting and other third-party services.

We recorded no such expenses in 2024 compared to $4.5 million recorded in 2023. These costs were related to integration following the Company’s acquisition of ECI and included license fees for systems in the process of being retired.

Restructuring and Related. We have been committed to streamlining operations and reducing operating costs by closing and consolidating certain facilities and reducing our worldwide workforce. Please see the additional discussion of our restructuring initiatives in the “Restructuring and Cost Reduction Initiatives” section of the Overview of this MD&A.

We recorded restructuring and related expense of $10.2 million in 2024, comprised of $4.1 of severance and related costs, and $6.1 million for variable and other facilities-related costs. In 2023, we recorded restructuring and related expense of $16.2

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million, comprised of $9.9 million for severance and related costs, and $6.3 million for variable and other facilities-related costs, including $1.0 million of net expense for the accelerated amortization of lease assets. Although we have eliminated positions as part of our restructuring initiatives, we continue to hire in certain areas that we believe are important to our future growth.

Interest Expense, net. Interest expense and interest income for the years ended December 31, 2024 and 2023 were as follows (in millions, except percentages):

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We had nominal interest income in both 2024 and 2023. Our interest expense in 2024 primarily represents interest, amortization of debt issuance costs and original issue discount, and the amortization of gains in accumulated other comprehensive (loss) income from the sales of our interest rate swap. Interest expense in 2024 was higher than 2023 primarily due to higher margins under our 2024 Term Loan compared to our 2020 Term Loan, and higher interest in 2024 due to our interest rate swap no longer being in place, partially offset by write-offs related to the refinancing of the 2020 Credit Facility with a portion of the proceeds from the 2024 Credit Facility on June 21, 2024. The write-offs related to the refinancing consisted of the remaining unamortized gains in accumulated other comprehensive (loss) income from the sales of our interest rate swap totaling $4.9 million, partially offset by the write-off of debt issuance costs from the 2020 Credit Facility totaling $2.0 million. Our interest expense in 2023 benefited from our interest rate swap that fixed the variable rate component of our interest rate at 0.904% and was sold in March 2023. See Note 15 to our consolidated financial statements for a discussion of the sale of our interest rate swap.

Other (Expense) Income, Net. Our other expense, net in 2024 was $29.1 million and was primarily comprised of $9.1 of fair value adjustments to the Preferred Stock and Warrants, $2.7 of accrued dividends and the $1.8 million call premium on our Preferred Stock that we redeemed on June 25, 2024, the $6.3 million write-off of an expired tax indemnity asset associated with the ECI Acquisition, and foreign currency exchange losses of $5.7 million. We recorded other expense, net, aggregating $3.8 million in 2023, primarily comprised of $5.3 million fair value adjustments for our Preferred Stock and Warrants, including dividends on the Preferred Stock, and $3.5 million of costs incurred in the Private Placement, partially offset by the gain of $7.3 million recognized from Accumulated other comprehensive income in connection with the sale of our interest rate swap.

Income Taxes. We recorded an income tax provision of $8.2 million and $10.8 million in 2024 and 2023, respectively.

During 2024 and 2023, we performed an analysis to determine if, based on all available evidence, we considered it more likely than not that some portion or all of the recorded deferred tax assets will not be realized in a future period. As a result of our evaluations, in 2024, for the U.S. deferred tax assets, we concluded that deferred tax assets are generally realizable, with the exception of certain federal and state net operating loss carryforwards, as well as certain tax credits, that are not anticipated to be utilized. Accordingly, we have maintained a valuation allowance on our U.S. deferred tax assets of $18.6 million. As a result of our evaluations for Israel, we maintained a full valuation allowance against our net deferred tax assets in Israel.

In October 2021, the Organization for Economic Co-operation and Development (the "OECD") announced the OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting, which agreed to a two-pillar solution to address tax challenges arising from digitalization of the economy. In December 2021, the OECD released Pillar Two Model Rules defining the global minimum tax rules, which contemplate a minimum tax rate of 15% (“Pillar Two”). In addition, the OECD issued administrative guidance providing transition and safe harbor rules that could delay the impact of the minimum tax directive. Certain countries in which we operate have enacted legislation consistent with the OECD model rules effective beginning in 2024. We considered the applicable tax laws in relevant jurisdictions and concluded there was no material effect on our tax provision for the year ended December 31, 2024. We will continue to evaluate the potential effect of Pillar Two rules on our future reporting periods, but we do not expect Pillar Two to have a significant impact on our results of operations, financial position, or cash flows.

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Years Ended December 31, 2023 and 2022

For a comparison of our results of operations for the fiscal years ended December 31, 2023 and 2022, see “Part II, Item 7. MD&A” of our Annual Report on Form 10-K for the year ended December 31, 2023, filed with the SEC on February 28, 2024.

Off-Balance Sheet Arrangements

We have no off-balance sheet arrangements that have or are reasonably likely to have a current or future material effect on our financial position, changes in financial position, revenue or expenses, results of operations, liquidity, capital expenditures or capital resources.

Liquidity and Capital Resources

Our consolidated statements of cash flows are summarized as follows (in thousands):

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We had cash, cash equivalents, and restricted cash aggregating $90 million and $27 million at December 31, 2024 and 2023, respectively. We had cash held by our non-U.S. subsidiaries aggregating approximately $18 million and $16 million at December 31, 2024 and 2023, respectively. If we elect to repatriate all of the funds held by our non-U.S. subsidiaries as of December 31, 2024, we do not believe that the amounts of potential withholding taxes that would arise from the repatriation would have a material effect on our liquidity.

On June 21, 2024, we entered into a Senior Secured Credit Facilities Credit Agreement (the “2024 Credit Facility” or “Credit Agreement”) as guarantor, with our wholly-owned subsidiary, Ribbon Communications Operating Company, Inc., as the borrower (“Borrower”), HPS Investment Partners, LLC ("HPS"), as administrative agent, and HPS and WhiteHorse Capital Management, LLC ("WhiteHorse" and, together with HPS, the "Lenders"), pursuant to which the Lenders provided us with a $385 million Credit Agreement comprised of (i) a $350 million term loan (the “2024 Term Loan”) and (ii) a $35 million revolving credit facility (the “2024 Revolver”), including a $20 million sublimit for letters of credit. The proceeds received from the 2024 Term Loan were used to (a) repay 100% of the amounts outstanding under the 2020 Credit Facility, (b) redeem in full the Preferred Stock and (c) pay fees and expenses related to the 2024 Credit Facility. Excess proceeds are being used by us for working capital and other general corporate purposes.

The 2024 Term Loan and the 2024 Revolver bear interest, at the Borrower’s option, at either the Alternate Base Rate (“ABR”) or Term Secured Overnight Financing Rate ("SOFR") with an Applicable Margin for each (all as defined in the 2024 Credit Facility). Margins for the first six months are 5.25% per annum for ABR Loans and 6.25% per annum for SOFR Loans. Thereafter, margins vary based on our Consolidated Net Leverage Ratio, ranging from 4.75% to 5.25% per annum for ABR Loans and 5.75% to 6.25% per annum for SOFR Loans. The 2024 Term Loan and the 2024 Revolver will both mature on June 21, 2029. The 2024 Term Loan is being repaid in equal quarterly installments: approximately $0.9 million beginning with the third quarter of 2024 through the second quarter of 2025; approximately $2.2 million beginning with the third quarter of 2025 and ending with the second quarter of 2027; and approximately $4.4 million quarterly thereafter, with the remaining principal balance of approximately $298.4 million due on the maturity date of June 21, 2029. In connection with the establishment of the 2024 Credit Facility, $7.7 million of original issue discount was withheld by the Lenders and we incurred $6.3 million of debt issuance costs for a total of $14.0 million that is being amortized to Interest expense, net over the term of the agreement.

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Our previous credit facility was the Senior Secured Credit Facilities Credit Agreement (as amended, the "2020 Credit Facility"), which we entered into on March 3, 2020, by and among us, as a guarantor, Ribbon Communications Operating Company, Inc., as the borrower (the "Borrower"), Citizens Bank, N.A., Santander Bank, N.A., and others as lenders, ("2020 Credit Facility Lenders"). For additional details regarding the terms of the 2024 Credit Facility and 2020 Credit Facility, see Note 14 to our consolidated financial statements.

On March 24, 2023, we entered into the Sixth Amendment to the 2020 Credit Facility (the “Sixth Amendment”) effective March 30, 2023. The Sixth Amendment, among other things, increased the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility), with the first, second and third quarters of 2023 increasing to 4.50:1.00. In the fourth quarter of 2023 and the first quarter of 2024, the Maximum Consolidated Net Leverage Ratio declined to 4.25:1.00 and 4.00:1.00, respectively. Also, the Sixth Amendment reduced the minimum Consolidated Fixed Charge Coverage Ratio (as defined in the 2020 Credit Facility) to 1.10:1.00 through the first quarter of 2024. The Sixth Amendment reduced the maximum borrowings allowed under the 2020 Revolving Credit Facility from $100 million to $75 million and the sublimit available for letters of credit was reduced from $30 million to $20 million. In addition, the Sixth Amendment replaced LIBOR with the Secured Overnight Financing Rate ("SOFR") as the alternative rate available to us for calculating interest owed under the 2020 Credit Facility with the margin fixed at 4.5%. In conjunction with the Sixth Amendment, we made a $75 million prepayment that was applied to the final payment due upon maturity in March 2025. The $75 million prepayment was almost entirely funded with the net proceeds from the Private Placement and the sales of our interest rate swap. Debt issuance costs associated with the Sixth Amendment totaled $1.7 million and were being amortized on a straight-line basis over the remaining life of the 2020 Credit Facility to Interest expense, net and were written off in conjunction with the early extinguishment of the 2020 Credit Facility on June 21, 2024.

The 2020 Credit Facility, as amended, allowed us to incur junior secured or unsecured debt in an amount no less than $50 million, subject to certain conditions, including the requirement that 50% of the aggregate amount of such incurred debt (net of certain costs, fees and other amounts) must be applied to prepay the 2020 Credit Facility and compliance with certain leverage ratio-based covenant exceptions. Quarterly principal payments were required on the 2020 Term Loan aggregating approximately $5.0 million per quarter through March 31, 2024, and if the refinancing had not occurred, $10.0 million would have been required in each of the three quarters thereafter, with the remaining and final payment due on the maturity date in March 2025.

At December 31, 2024, we had an outstanding balance under the 2024 Term Loan of $348.3 million at an average interest rate of 10.6%, with no revolver balance and no letters of credit outstanding under our 2024 Credit Facility. Our interest rates under our 2020 Term Loan for the year ended December 31, 2023 benefited from a hedge instrument that was in place, specifically a fixed rate swap, which was sold in March 2023 (see Note 10). We were in compliance with all covenants of the 2024 Credit Facility and 2020 Credit Facility at December 31, 2024 and 2023, respectively, including the Consolidated Net Leverage Ratio calculation under the 2020 Credit Facility that considered our debt to include Preferred Stock.

We use letters of credit, bank guarantees and surety bonds in the course of our business. At December 31, 2024, we had $10.9 million of letters of credit, bank guarantees, and surety bonds outstanding (collectively, "Guarantees") under various uncommitted facilities and no letters of credit outstanding under the 2024 Credit Facility. At December 31, 2023, we had Guarantees aggregating $7.9 million, comprised of $2.7 million of letters of credit under the 2020 Credit Facility described above and $5.2 million of Other Guarantees. At December 31, 2024 and 2023, we had cash collateral of $2.7 million and $0.1 million, respectively, supporting the Guarantees, which are reported in Restricted cash in our consolidated balance sheets.

We are exposed to financial market risk related to foreign currency fluctuations and changes in interest rates. These exposures are actively monitored by management. To manage the volatility related to the exposure to changes in interest rates, we may enter into a derivative financial instrument. Management’s objective has been to reduce, where it is deemed appropriate to do so, fluctuations in earnings and cash flows associated with changes in interest rates. Our policies and practices are to use derivative financial instruments only to the extent necessary to manage exposures. We do not hold or issue derivative financial instruments for trading or speculative purposes.

As a result of exposure to interest rate movements, during March 2020, we entered into an interest rate swap arrangement, which effectively converted our $400 million term loan with its variable interest rate based upon one-month LIBOR to an aggregate fixed rate of 0.904%, plus a leverage-based margin as defined in the 2020 Credit Facility. On July 22, 2022, we sold $30 million of the notional amount of our interest rate swap back to our counterparty for $1.5 million, reducing the notional amount of this swap to $370 million. On August 16, 2022, we sold another $30 million of the notional amount of our interest

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rate swap back to our counterparty for $1.6 million, reducing the notional amount to $340 million, which approximated the term loan debt then outstanding. The gain in accumulated other comprehensive (loss) income related to the $60 million notional amount sold of $3.1 million was being released into earnings on a straight line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense, the amortization of which totaled $0.4 million and $0.9 million for the years ended December 31, 2024 and 2023, respectively. The remaining unamortized gain in accumulated other comprehensive (loss) income of approximately $0.5 million was written off to interest expense in conjunction with the refinancing of the 2020 Credit Facility on June 21, 2024. On March 24, 2023, we received $9.4 million, consisting of $0.4 million of interest and $9.0 million for the sale of $170 million of our $340 million notional amount interest rate swap back to our counterparty, reducing the notional amount to $170 million. On March 27, 2023, we received $9.8 million, consisting of $0.4 million of interest and $9.4 million for the sale of the remaining $170 million of our interest rate swap back to our counterparty. The portion of the gain in accumulated other comprehensive (loss) income related to the term loan debt prepaid on the date of the final sale of our swap totaled $7.3 million and was released into earnings immediately as Other expense, net. The portion of the gain in accumulated other comprehensive (loss) income related to our remaining term loan debt balance totaled $12.0 million and was being released into earnings on a straight line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense beginning in the second quarter of 2023, the amortization of which was $3.0 million and $4.7 million for the years ended December 31, 2024 and 2023, respectively. The remaining unamortized gain in accumulated other comprehensive (loss) income of $4.4 million was written off to interest expense in conjunction with the refinancing of the 2020 Credit Facility on June 21, 2024.

Our objectives in using interest rate derivatives have been to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we have used an interest rate swap as part of our interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for making fixed-rate payments over the life of an agreement without exchange of the underlying notional amount.

The effective portion of changes in the fair value of designated derivatives that qualify as cash flow hedges is recorded in Accumulated other comprehensive income in the consolidated balance sheet and is subsequently reclassified into earnings in the period that the hedged forecasted transactions affect earnings. During the year ended December 31, 2023, such a derivative was used to hedge the variable cash flows associated with the outstanding borrowings under the 2020 Credit Facility and we accounted for this derivative as an effective hedge until the final portion of the swap was sold on March 27, 2023. Any ineffective portion of the change in fair value of the derivative would be recognized directly in earnings. However, we recorded no hedge ineffectiveness over the life of our swap. In the year ended December 31, 2023, we recorded $7.3 million of Other expense, net due to the sale of our interest rate swap arrangement.

Cash Flows from Operating Activities

Our primary source of cash from operating activities has been from cash collections from our customers. We expect cash flows from operating activities to be affected by increases and decreases in sales volumes and timing of collections, and by purchases and shipments of inventory. Our primary uses of cash from operating activities have been for personnel costs and investment in our research and development and in our sales and marketing, and general and administrative departments.

Our operating activities provided cash of $50.2 million in 2024, primarily as a result of lower other operating assets and accounts receivable, the increase in the fair value of our preferred stock and warrant liabilities, and higher deferred revenue. These amounts were partially offset by lower accounts payable, accrued expenses and other long-term liabilities, and higher inventory. Our net loss was more than offset by adjustments for certain non-cash expenses, such as amortization of intangible assets and stock-based compensation. These adjustments were partially offset by a $6.7 million one-time payment of accumulated dividends as a result of our redemption of our Preferred Stock liability on June 25, 2024, $8.2 million of amortization of an accumulated other comprehensive gain related to our interest rate swap, and $16.9 million of deferred income tax expense. Higher revenue in our Cloud and Edge segment and lower operating expenses company-wide due to our various cost saving initiatives, including lower employee and facilities expenses, continue to positively affect our operating cash flow.

Our operating activities provided $17.1 million of cash in 2023, primarily resulting from our net loss, which was more than offset by certain non-cash expenses, such as amortization of intangible assets, stock-based compensation, depreciation and amortization of property and equipment, amortization of debt issuance costs and the change in the fair value of our preferred stock and warrant liabilities, including dividends on our preferred stock, partially offset by deferred income taxes and the gain

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on the sale of our interest rate swap. Also, the changes in our operating assets and liabilities provided operating cash, including lower other operating assets and accounts receivable, partially offset by lower accrued expenses and other long-term liabilities, higher inventory, and lower accounts payable. Higher product revenue in our IP Optical Networks segment and lower operating expenses company-wide due to our various cost saving initiatives, including lower employee and facilities expenses, all positively affected our operating cash flow in 2023.

Cash Flows from Investing Activities

Our investing activities used cash of $22.9 million and $9.5 million in 2024 and 2023, respectively. Our investing activities were primarily used to purchase property and equipment. The $13.4 million increase in purchases of property and equipment in 2024 compared to 2023 is primarily due to the build out of a new facility in Israel.

Cash Flows from Financing Activities

Our financing activities provided $37.7 million of cash in 2024. We received $342.3 million of proceeds, net of $7.7 million of original issue discount, from the issuance of term debt under the 2024 Credit Facility that was established on June 21, 2024 to refinance the 2020 Credit Facility. Also, we had $44.1 million of both borrowings and principal payments under the 2020 Revolving Credit Facility. In conjunction with the establishment of the 2024 Credit Facility, we repaid the 2020 Term Debt amounting to $235.4 million, redeemed all of the outstanding Preferred Stock totaling $56.9 million, and paid $6.3 million in debt issuance costs. Also, we paid $1.8 million in principal payments on our 2024 Term Debt. In addition, we paid $4.3 million of tax obligations related to the vesting of stock awards and units.

Our financing activities used $47.9 million of cash in 2023, primarily due to $95.1 million of principal payments on our term debt, including a $75.0 million prepayment in connection with the Sixth Amendment to the 2020 Credit Facility, $1.7 million of debt issuance costs also paid in connection with the Sixth Amendment, and $4.5 million for the payment of tax withholding related to the net share settlements of restricted stock awards upon vesting. In addition, we received $53.4 million of proceeds from the issuance of the Preferred Stock and Warrants in the Private Placement.

The rate at which we consume cash is dependent upon the cash needs of our future operations, including our contractual obligations at December 31, 2024, primarily comprised of our debt principal and interest obligations as described above, and our operating lease and purchase obligations. Our operating lease obligations totaled $57.0 million at December 31, 2024, with payments to be made aggregating $12.7 million in 2025, $11.5 million in 2026, $10.2 million in 2027 and $22.6 million thereafter. Our purchase obligations totaled $106.6 million at December 31, 2024, with estimated payments aggregating $96.2 million in 2025 and $10.4 million thereafter. We anticipate devoting substantial capital resources to continue our R&D efforts, to maintain our sales, support and marketing, and for other general corporate activities. We believe that our financial resources, along with managing discretionary expenses, will allow us to manage the ongoing impact of inflation on our business operations. Looking ahead, we have developed contingency plans to reduce costs further if the situation deteriorates.

Based on our current expectations, we believe our current cash balances and available borrowings under the 2024 Credit Facility will be sufficient to meet our anticipated cash needs for working capital and capital expenditures for at least twelve months from the date of issuance of these financial statements.

Recent Accounting Pronouncements

In November 2024, the Financial Accounting Standards Board (the "FASB") issued ASU 2024-03, Income Statement, Reporting Comprehensive Income: Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”), which requires disaggregation of certain expense captions into specified categories in disclosures within the footnotes to the financial statements. The objective of this standard is to provide investors with information to better understand a public entity’s performance and prospects for future cash flows, and to compare their performance over time with that of other entities. ASU 2024-03 will be effective for us beginning with our 2027 annual financial statements and interim financial statements thereafter, with early adoption permitted. The adoption of ASU 2024-03 will require us to provide new footnote disclosure about the types of expenses that are included in certain captions on our Statements of Operations, such as Cost of revenue, Research and development, Sales and marketing, and General and administrative.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which increases the disclosure requirements around rate reconciliation information and certain types of

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income taxes companies are required to pay. ASU 2023-09 will be effective for us beginning with our 2025 annual financial statements, with early adoption permitted. We expect the adoption of the standard will require certain additional income tax disclosures.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which improves reportable segment disclosure requirements, including enhancement of the disclosures of significant segment expenses and interim disclosure requirements to enable investors to better understand an entity’s overall performance and assess potential future cash flows. ASU 2023-07 became effective for us beginning with this Annual Report on Form 10-K which includes the required additional segment disclosures.

Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with our financial statements and the related notes included in Item 8, "Financial Statements and Supplementary Data” in this Annual Report on Form 10-K. This discussion contains forward-looking statements that reflect our plans, estimates and beliefs and involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of various factors including, but not limited to, those disclosed in Item 1A, “Risk Factors”, elsewhere in this Annual Report on Form 10-K, in other documents filed with the SEC and otherwise publicly disclosed. Please refer to “Cautionary Note Regarding Forward-Looking Statements” above for additional information. For a complete description of our business and other important information, please refer to Item 1 of Part I of this Annual Report on Form 10-K.

Overview

We are a leading global provider of communications technology to service providers and enterprises. We provide a broad range of software and high-performance hardware products, network solutions, and services that enable the secure delivery of data and voice communications, and high-bandwidth networking and connectivity for residential consumers and for small, medium, and large enterprises and industry verticals such as finance, education, government, utilities, and transportation. Our mission is to create a recognized global technology leader providing cloud-centric solutions that enable the secure exchange of information, with unparalleled scale, performance and elasticity. We are headquartered in Plano, Texas, and have a global presence with research and development or sales and support locations in over thirty countries around the world.

Key Trends and Economic Factors Affecting Ribbon

Supplier Disruptions. Ongoing uncertainty in the global economy due to inflation, the wars in Israel and Ukraine, national security concerns and other factors, continue to disrupt various manufacturing, commodity and financial markets, increase volatility, and impede global supply chains. Our ability to deliver our solutions as agreed upon with our customers depends in part on the ability of our global contract manufacturers, vendors, licensors and other business partners to deliver products or perform services we have procured from them.

Continued uncertain global economic conditions, may cause our customers to restrict spending or delay purchases for an indeterminate period of time and consequently cause our revenues to decline. Further, such factors may negatively impact our operating costs resulting in a reduction in net income. The degree to which the ongoing wars in Israel and Ukraine and the inflationary and high interest rate environment impacts our future business, financial position and results of operations will depend on developments beyond our control, including the duration of the global economic downturn that has resulted from these factors.

The Ongoing Wars in Israel and Ukraine. The uncertainty resulting from the wars in Israel and Ukraine and the threat for expansion of one or both of these wars could result in some of our customers delaying purchases from us. As a result of safety concerns, we may close our offices in Israel from time to time. Although our employees in these offices have the ability to work remotely and business continuity plans are in place to address any medium- or long-term disruptions that could result from the closure of these offices, the office closures and general effects of employees operating in a region at war could have a negative impact on our operations. Further, a number of our employees in Israel are members of the military reserves and subject to immediate call-up in response to the war in Israel. Following the terrorist attacks in Israel in October 2023, a number of our employees have been activated for military duty and we expect that additional employees will also be activated if the war in Israel continues. While we have business continuity plans in place to address the military call-ups, it could affect the timing of projects in the short-term as the work is shifted to other team members both inside and outside of Israel.

Further, the U.S. and other European countries have imposed sanctions and trade restrictions against Russia in connection with the war in Ukraine. These sanctions and restrictions currently prohibit our ability to sell certain products and services. The sanctions continue to evolve and further changes in the current sanctions or trade restrictions could further limit our ability to sell products and services to customers in Russia and, our ability to collect on outstanding accounts receivable from such customers. If we are further limited in our ability to sell products and services to Russia and other countries for an extended period, it could have a material impact on our financial results.

Inflation and Interest Rates. We continue to see near-term impacts on our business due to inflation, including ongoing global price pressures driving up energy prices, component costs, freight premiums, and other operating costs above normal rates. Although headline inflation in the United States and Europe appears to have reached a peak, core inflation (excluding food and energy prices) remains elevated and is a source of continued cost pressure on businesses and households. Interest rates have increased significantly as central banks in developed countries attempt to subdue inflation while government deficits and debt remain at high levels in many global markets. Accordingly, the eventual implications of higher government deficits and debt, tighter monetary policy, and potentially higher long-term interest rates may drive a higher cost of capital for our business.

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Presentation

Unless otherwise noted, all financial amounts, excluding tabular information, in this Management's Discussion and Analysis of Financial Condition and Results of Operations ("MD&A") are rounded to the nearest million dollar amount, and all percentages, excluding tabular information, are rounded to the nearest percentage point.

Private Placement

On March 28, 2023, we issued 55,000 shares of newly designated Series A Preferred Stock (the "Preferred Stock") to investors in a private placement offering at a price of $970 per share, along with 4.9 million warrants (the "Warrants") to purchase shares of our common stock, par value $0.0001 per share (the "Private Placement"), at an exercise price of $3.77 per share. The proceeds from the Private Placement were approximately $53.4 million, including approximately $10 million from existing related party stockholders. For additional detail on the Private Placement, see Note 16 - Preferred Stock and Warrants to our consolidated financial statements.

2023 Restructuring Plan

In February 2023, our Board of Directors approved a strategic restructuring program (the "2023 Restructuring Plan") to streamline our operations in order to support our investment in critical growth areas. The 2023 Restructuring Plan includes, among other things, charges related to a workforce reduction. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements.

We recorded restructuring and related expense of $9.9 million in the year ended December 31, 2023 in connection with the 2023 Restructuring Plan for severance related costs. We anticipate that we will record nominal future expense for severance in connection with the 2023 Restructuring Plan.

Operating Segments

Our CODM assesses our performance based on the performance of two separate organizations within Ribbon, the Cloud and Edge operating segment ("Cloud and Edge") and the IP Optical Networks operating segment ("IP Optical Networks"). For additional details regarding our operating segments, see Note 18 - Operating Segment Information to our consolidated financial statements.

Financial Overview

Financial Results

We reported a loss from operations of $24.3 million for 2023 and $48.3 million for 2022. We reported a net loss of $66.2 million for 2023 and $98.1 million for 2022.

Our revenue was $826.3 million in 2023, comprised of $477.6 million attributable to Cloud and Edge and $348.7 million attributable to IP Optical Networks. Our revenue was $819.8 million in 2022, comprised of $508.2 million attributable to Cloud and Edge and $311.6 million attributable to IP Optical Networks. Our gross profit was $408.1 million in 2023, comprised of $300.0 million attributable to Cloud and Edge and $108.1 million attributable to IP Optical Networks. Our gross profit was $400.9 million in 2022, comprised of $310.3 million attributable to Cloud and Edge and $90.6 million attributable to IP Optical Networks. Our gross margin was 49.4% in 2023 and 48.9% in 2022. In 2023, our Cloud and Edge gross margin was 62.8% and our IP Optical Networks gross margin was 31.0%. In 2022, our Cloud and Edge gross margin was 61.1% and our IP Optical Networks gross margin was 29.1%.

Our operating expenses were $432.4 million in 2023 and $449.3 million in 2022. Our 2023 operating expenses included $28.6 million of amortization of acquired intangible assets, $4.5 million of acquisition-, disposal- and integration-related expense, and $16.2 million of restructuring and related expense. Our 2022 operating expenses included $29.6 million of amortization of acquired intangible assets, $6.3 million of acquisition-, disposal- and integration-related expense, and $10.8 million of restructuring and related expense.

We recorded stock-based compensation expense of $21.8 million in 2023 and $18.7 million in 2022.

See "Results of Operations" in this MD&A for additional discussion of our results of operations for the years ended December 31, 2023 and 2022.

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Restructuring and Cost Reduction Initiatives

In February 2023, our Board of Directors approved the 2023 Restructuring Plan to streamline our operations in order to support our investment in critical growth areas. The 2023 Restructuring Plan includes, among other things, charges related to a workforce reduction. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements. We recorded restructuring and related expense of $9.9 million in 2023 in connection with the 2023 Restructuring Plan for severance related costs for approximately 200 employees. We anticipate that we will record nominal future expense for severance in connection with the 2023 Restructuring Plan.

In February 2022, our Board of Directors approved the 2022 Restructuring Plan to streamline our operations in order to support our investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2022 Restructuring Plan, we recorded restructuring and related expense of $6.3 million in 2023, comprised of $5.3 million for variable and other facilities-related costs and $1.0 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease. In 2022, we recorded $10.2 million of expense for the 2022 Restructuring Plan, comprised of $3.3 million for variable and other facilities-related costs, $1.6 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease, and $5.3 million for severance and related costs for approximately 70 employees. We anticipate that we will expense $5 million in 2024 related to the 2022 Restructuring Plan.

In 2020, we implemented a restructuring plan to eliminate certain positions and redundant facilities, primarily in connection with the ECI Acquisition, to further streamline our global footprint and improve our operations (the "2020 Restructuring Initiative"). In connection with the 2020 Restructuring Initiative, we eliminated duplicate functions arising from the ECI Acquisition in support of our efforts to integrate the two companies. In connection with the 2020 Restructuring Initiative, we recorded no expense in 2023, a nominal amount of restructuring and related expense in 2022 and $4.7 million of such expense in 2021. The 2021 amount was comprised of $4.6 million for severance and related costs for approximately 60 employees and $0.1 million for variable and other facilities-related costs. All amounts will be fully paid in 2024. We do not expect to record any future restructuring and related expense under the 2020 Restructuring Initiative.

In 2019, we implemented a restructuring plan to streamline our global footprint, improve our operations and enhance our customer delivery (the "2019 Restructuring Initiative"). The 2019 Restructuring Initiative includes facility consolidations, refinement of our research and development activities, and a reduction in workforce. The facility consolidations under the 2019 Restructuring Initiative (the "Facilities Initiative") included a consolidation of our North Texas sites into a single campus, housing engineering, customer training and support, and administrative functions, as well as a reduction or elimination of certain excess and duplicative facilities worldwide. In addition, the Facilities Initiative included consolidating our global software laboratories and server farms into two lower cost North American sites. We continue to evaluate our properties included in the Facilities Initiative for accelerated amortization and/or right-of-use asset impairment. We expect that the actions under the Facilities Initiative will be substantially completed in 2024. In connection with the 2019 Restructuring Initiative, we recorded no restructuring and related expense in 2023, $0.7 million in 2022 comprised entirely of facilities related expense and $7.0 million of such expense in 2021, comprised of $5.7 million for variable and other facilities-related costs and $1.3 million of net expense for accelerated amortization of lease assets. The amount of $1.3 million for accelerated amortization of lease assets was comprised of $3.4 million of expense, partially offset by $2.1 million of income related to a lease modification for one of our restructured lease facilities. The amount initially accrued for severance and related costs under this 2019 Restructuring Initiative was paid in 2021.

Accelerated rent amortization is recognized from the date that we commence the plan to fully or partially vacate a facility, for which there is no intent or ability to enter into a sublease, through the final vacate date. We recorded $1.0 million, $1.6 million and $3.4 million of expense for accelerated rent amortization in the years ended December 31, 2023, 2022 and 2021, respectively. These amounts are included as components of Restructuring and related expense in our statements of operations, reducing our Operating lease right-of-use assets in our consolidated balance sheets at the end of each respective year. We continue to evaluate our properties included in the Facilities Initiative for accelerated amortization and/or right-of-use asset impairment. We may incur additional future expense if we are unable to sublease other locations included in the Facilities Initiative.

Critical Accounting Policies and Estimates

This MD&A is based upon our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of these financial statements requires us to make

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estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosure of contingent assets and liabilities. We base our estimates and judgments on historical experience, knowledge of current conditions and beliefs of what could occur in the future given available information. We consider the following accounting policies to be both those most important to the portrayal of our financial condition and those that require the most subjective judgment. The significant accounting policies that we believe are the most critical include revenue recognition, the valuation of inventory, debentures and warrants received as sale consideration, warranty accruals, loss contingencies and reserves, stock-based compensation, the Preferred Stock and Warrants, business combinations, goodwill and intangible assets, accounting for leases, and accounting for income taxes. If actual results differ significantly from management's estimates and projections, there could be a material effect on our consolidated financial statements.

Revenue Recognition. We derive revenue from two primary sources: products and services. Product revenue is generated from sales of our stand-alone software, as well as software with attached hardware that function together to deliver the products' essential functionality. Both software and hardware are also sold on a standalone basis. Services include customer support (software updates and technical support), consulting, design services, installation services and training. A typical contract includes both product and services. Generally, contracts with customers contain multiple performance obligations. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to the separate performance obligations on a relative standalone selling price basis. SSPs are typically estimated using all observable transactions, including when products and services are sold on a standalone basis.

The software licenses typically provide a perpetual right to use our software. We also sell term-based software licenses that expire and Software-as-as-Service ("SaaS")-based software, which are referred to as subscription arrangements. We do not customize our software nor are installation services required, as the customer has a right to utilize internal resources or a third-party service company. The software and hardware are delivered before related services are provided and are functional without professional services or customer support. We have concluded that our software licenses are functional intellectual property that are distinct, as the user can benefit from the software on its own. The product revenue is typically recognized upon transfer of control or when the software is made available for download, as this is the point that the user of the software can direct the use of, and obtain substantially all of the remaining benefits from, the functional intellectual property. We begin to recognize software revenue related to the renewal of subscription software licenses at the start of the subscription period.

Service revenue includes revenue from customer support and other professional services. We offer warranties on our products. Certain of our warranties are considered to be assurance-type in nature, ensuring that the product is functioning as intended. Assurance-type warranties do not represent separate performance obligations. We also sell separately-priced maintenance service contracts which qualify as service-type warranties and represent separate performance obligations. We do not allow and have no history of accepting product returns.

Customer support includes software updates on a when-and-if-available basis, telephone support, integrated web-based support and bug fixes or patches. We sell our customer support contracts at a percentage of list or net product price related to the support. Customer support revenue is recognized ratably over the term of the customer support agreement, which is typically one year.

Our professional services include consulting, technical support, resident engineer services, design services and installation services. Because control transfers over time, revenue is recognized based on progress toward completion of the performance obligation. The method to measure progress toward completion requires judgment and is based on the nature of the products or services to be provided. We generally use the input method to measure progress for our contracts because we believe it best depicts the transfer of assets to the customer which occurs as we incur costs for the contracts. However, in some instances, we use the output method because it best depicts the transfer of asset to the customer. Under the cost-to-cost measure of progress, the progress toward completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. When the measure of progress is based upon expended labor, progress toward completion is measured as the ratio of labor time expended to date versus the total estimated labor time required to complete the performance obligation. Revenue is recorded proportionally as costs are incurred or as labor is expended. Costs to fulfill these obligations include internal labor as well as subcontractor costs.

We offer customer training courses, for which the related revenue is typically recognized as the training services are performed.

Our contracts with customers often include promises to transfer multiple products and services to the customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment.

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Judgment is required to determine the SSP for each distinct performance obligation. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information such as the size of the customer and geographic region in determining the SSP.

Valuation of Inventory. We review inventory for both potential obsolescence and potential loss of value periodically. In this review, we make assumptions about the future demand for and market value of the inventory and, based on these assumptions, estimate the amount of any excess, obsolete or slow-moving inventory.

We write down our inventories if they are considered to be obsolete or at levels in excess of forecasted demand. In these cases, inventory is written down to estimated realizable value based on historical usage and expected demand. Inherent in our estimates of market value in determining inventory valuation are estimates related to economic trends, future demand for our products and technical obsolescence of our products. If future demand or market conditions are less favorable than our projections, additional inventory write-downs could be required and would be reflected in the cost of revenue in the period the revision is made. To date, we have not been required to revise any of our assumptions or estimates used in determining our inventory valuations.

We write down our evaluation equipment at the time of shipment to our customers, as it is not probable that the inventory value will be realizable.

Investments. We received debentures (the "Debentures") and warrants (the "AVCT Warrants") as sale consideration in connection with our December 1, 2020 sale of the Kandy Communications Business to American Virtual Cloud Technologies, Inc. ("AVCT") (the "Kandy Sale"). On September 8, 2021 (the "Debenture Conversion Date"), the Debentures were converted into shares of AVCT common stock (the "Debenture Shares"). In connection with the conversion of the Debentures to the Debenture Shares, we elected to use the fair value option to account for its equity investment in AVCT as permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), which then refers to ASC 820, Fair Value Measurement ("ASC 820") to provide the fair value framework for valuing such investments. In accordance with ASC 820, we recorded the investment in AVCT at fair value, with changes in fair value recorded as a component of Other (expense) income, net, in the consolidated statements of operations.

On August 29, 2022, we and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of our investment in the Debenture Shares and the AVCT Warrants. Pursuant to the settlement agreement, we also entered into a Wind Down Agreement with AVCT, pursuant to which a Reseller Agreement between the parties, as previously amended, was terminated, and we were granted a non-exclusive perpetual license to use and modify certain intellectual property owned by AVCT comprising WebRTC gateway technology that is integrated with Ribbon's SBCs and Application Servers. The perpetual license granted by AVCT is classified as Intangible assets, net in our consolidated balance sheets.

Warranty Accruals. We record warranty liabilities for estimated costs of fulfilling our obligations under standard limited hardware and software warranties at the time of sale. The liability for standard warranties is included in Accrued expenses and other and Other long-term liabilities in our consolidated balance sheet. The specific warranty terms and conditions vary depending upon the country in which we do business, but generally include material costs, technical support, labor and associated overhead over a period ranging from one to three years. We provide for the estimated costs to fulfill customer warranty obligations for certain of our products upon recognition of the related revenue. Warranty is included as a component of Cost of revenue in our consolidated statements of operations, and is determined based on actual warranty cost experience, estimates of component failure rates and our management's industry experience. Our sales contracts do not permit the right of return of the product by the customer after the product has been accepted.

Loss Contingencies and Reserves. We are subject to ongoing business risks arising in the ordinary course of business that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. We regularly evaluate current information available to determine whether such amounts should be adjusted and record changes in estimates in the period they become known. We are subject to various legal claims. We reserve for legal contingencies and legal fees when the amounts are probable and reasonably estimable.

Stock-Based Compensation. Our stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which is generally the vesting period.

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We use the Black-Scholes valuation model for estimating the fair value on the date of grant of employee stock options. Determining the fair value of stock option awards at the grant date requires judgment regarding certain valuation assumptions, including the volatility of our stock price, expected term of the option, risk-free interest rate and expected dividends. Changes in such assumptions and estimates could result in different fair values and could therefore impact our earnings. Such changes, however, would not impact our cash flows. The fair value of restricted stock awards, restricted stock units and performance-based awards is based upon our stock price on the grant date.

We grant performance-based stock units, some of which include a market condition, to certain of our executives and certain other employees. We use a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity, and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values. We are required to record expense through the respective final vesting dates regardless of the number of shares that are ultimately earned. Once the grant date criteria have been met for a fiscal year performance period, we record stock-based compensation expense based on our assessment of the probability that the respective performance condition will be achieved and the level, if any, of such achievement. The Compensation Committee determines the number of shares earned, if any, after our financial results for each fiscal year performance period are finalized. Upon determination by the Compensation Committee of the number of shares that will be received upon vesting, such number of shares becomes fixed and the unamortized expense is recorded through the remainder of the service period, at which time any performance-based stock units earned will vest pending each executive's continued employment with us through that date.

The amount of stock-based compensation expense recorded in any period for unvested awards requires estimates of the amount of stock-based awards that are expected to be forfeited prior to vesting, as well as assumptions regarding the probability that performance-based stock awards without market conditions will be earned.

Preferred Stock and Warrants. We account for the Preferred Stock and Warrants as liability-classified instruments based on an assessment of their specific terms in accordance with ASC Topic 480, Distinguishing Liabilities from Equity. The fair value option was elected for the Preferred Stock, as we consider fair value to best reflect the expected future economic value. These liabilities are remeasured to fair value at each reporting date using the same valuation methodology applied upon issuance. The Preferred Stock is considered to be debt for our Consolidated Net Leverage Ratio covenant calculation required under our 2020 Credit Facility.

Business Combinations. We allocate the purchase price of acquired companies to identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. Significant management judgments and assumptions are required in determining the fair value of assets acquired and liabilities assumed, particularly acquired intangible assets which are principally based upon estimates of the future performance and cash flows expected from the acquired business and applied discount rates. While we use our best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at a business combination date, our estimates and assumptions are inherently uncertain and subject to refinement. If different assumptions are used, it could materially impact the purchase price allocation and our financial position and results of operations. Any adjustments to assets acquired or liabilities assumed subsequent to the purchase price allocation period are included in operating results in the period in which the adjustments are determined. Intangible assets typically are comprised of in-process research and development, developed technology, customer relationships, trade names and internal use software.

Goodwill and Intangible Assets. Goodwill is not amortized, but instead is tested for impairment annually, or more frequently if indicators of potential impairment exist. Intangible assets with estimated lives and other long-lived assets are reviewed for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by comparing the carrying amount of the asset to future net undiscounted pretax cash flows expected to be generated by the asset. If these comparisons indicate that an asset is not recoverable, we will recognize an impairment loss for the amount by which the carrying value of the asset exceeds the related estimated fair value.

We perform a fair value analysis for each reporting unit using both an income and market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. We assesse each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately. Any impairment charges are reported separately in our consolidated statements of operations.

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Judgment is required in determining whether an event has occurred that may impair the value of goodwill, identifiable intangible assets or other long-lived assets. Factors that could indicate an impairment may exist include significant underperformance relative to plan or long-term projections, strategic changes in business strategy, significant negative industry or economic trends, a significant change in circumstances relative to a large customer, a significant decline in our stock price for a sustained period and a decline in our market capitalization to below net book value. We must make assumptions about future control premiums, market comparables, cash flows, operating plans, discount rates and other factors to determine recoverability.

Our annual testing for impairment of goodwill is completed as of October 1. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may be either an operating segment or a portion of an operating segment. Our reporting units are our two operating segments, Cloud and Edge and IP Optical Networks. For our annual impairment testing, we perform a fair value analysis using both an Income and Market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. We assess each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately.

Based upon the completion of our 2023 and 2022 annual test for goodwill impairment, we determined that there was no impairment of goodwill for either of our reporting units. The results of our 2021 impairment test determined that the carrying value of our IP Optical Networks segment exceeded its fair value. The amount of the impairment of $116.0 million was recorded in the fourth quarter of 2021 and is reported separately in our consolidated statement of operations for the year ended December 31, 2021. We determined that there was no impairment of our Cloud and Edge segment in 2021.

Leases. We account for our leases in accordance with Accounting Standards Codification ("ASC") 842, Leases ("ASC 842"). We have operating leases for corporate offices, and research and development facilities and historically had finance leases for certain equipment. Operating leases are reported separately in our consolidated balance sheets. Assets acquired under finance leases, if any, are included in Property and equipment, net, in the consolidated balance sheets.

We determine if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides us with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, we do not separate lease and non-lease components but rather, account for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term.

For operating leases, lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases includes both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. We expense all variable lease costs as incurred.

Accounting for Income Taxes. Our provision for income taxes is comprised of both current taxes and deferred taxes. The current income tax provision is generally calculated as the estimated taxes payable or refundable on tax returns to be filed for the year ended December 31, 2023. We provide for deferred income taxes based on temporary differences between financial and taxable income, net operating loss carryforwards, tax credit carryforwards and any required valuation allowances.

We assess the recoverability of all deferred tax assets recorded on the balance sheet and provide any necessary valuation allowances as required. In evaluating our ability to realize our deferred tax assets, we consider all available positive and negative evidence, including our past operating results, the existence of cumulative income in the most recent years, changes in our business operations, and our forecast of future taxable income. In determining future taxable income, we make assumptions, including the amount of state, federal and international pre-tax income, the reversal of temporary differences and the implementation of feasible and prudent tax planning strategies. These assumptions require significant judgment about the forecasts of future taxable income and are consistent with the plans and estimates we are using to manage our underlying businesses. Such assessment is completed on a jurisdiction-by-jurisdiction basis.

We have provided for income taxes on the undistributed earnings of our non-U.S. subsidiaries as of December 31, 2023, excluding Ireland and Israel, which are indefinitely reinvested. Accordingly, we are required to recognize deferred taxes for 2023 on the outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings.

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We assess all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position's sustainability and is measured at the largest amount of benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and we determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of recognized tax benefit is still appropriate. The recognition and measurement of tax benefits require significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Results of Operations

Years Ended December 31, 2023 and 2022

Revenue. Revenue for the years ended December 31, 2023 and 2022 was as follows (in thousands, except percentages):

Segment revenue for the years ended December 31, 2023 and 2022 was as follows (in thousands):

The increase in our product revenue in 2023 compared to 2022 was primarily the result of $33 million of higher sales of our IP Optical Networks products, offset by $31 million of lower sales of our Cloud and Edge products. The increase in revenue from the sale of IP Optical Networks products was primarily attributable to higher sales in India and the U.S. markets following the introduction of new products and capabilities, including support for Long Haul Optical Transport, 5G Cell Site Routers, and a new series of IP Routers. The decrease in revenue from the sale of Cloud and Edge products was primarily attributable to lower sales to U.S. Tier One service providers, partially offset by increased sales to Enterprise customers, including U.S. Federal agencies to support voice network modernization.

Revenue from sales to enterprise customers was 32% and 28% of our product revenue in 2023 and 2022, respectively. These sales were made through both our direct sales team and indirect sales channel partners.

Revenue from indirect sales through our channel partner program was 35% and 30% of our product revenue in 2023 and 2022, respectively. The increase in channel sales reflects stronger deployments through systems integrators as well as sell-through from our Service Provider channel partners.

The timing of the completion of customer projects and revenue recognition criteria satisfaction may cause our product revenue to fluctuate from one period to the next.

Service revenue is primarily comprised of software and hardware maintenance and support (“maintenance revenue”) and network design, installation and other professional services (“professional services revenue”).

Service revenue for the years ended December 31, 2023 and 2022 was comprised of the following (in thousands, except percentages):

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Segment service revenue for the years ended December 31, 2022 and 2021 was comprised of the following (in thousands):

Total service revenue from our Cloud and Edge segment was slightly higher in 2023 compared to 2022 due to a $3 million increase in professional services revenue and a decline in maintenance revenue. The increase in professional services revenue is related to the timing and completion of certain projects to both service providers and enterprise customers. The lower maintenance revenue reflects decommissioning of older equipment with several customers. Service revenue from our IP Optical Networks segment increased by 4.2% in 2023 compared to 2022, primarily due to an increase in projects driven by higher product sales.

The following customer contributed 10% or more of our revenue in the years ended December 31, 2023 and 2022:

Revenue earned from customers domiciled outside the United States was 58% and 57% of total revenue in 2023 and 2022, respectively. Due to the timing of project completions, we expect that the domestic and international components as a percentage of our revenue may fluctuate from quarter to quarter and year to year. Our total revenue for the years ended December 31, 2023 and 2022 was disaggregated geographically as follows (in thousands):

Our deferred product revenue was $17 million at December 31, 2023 and $29 million at December 31, 2022. Our deferred service revenue was $116 million at December 31, 2023 and $104 million at December 31, 2022. Our deferred revenue balance may fluctuate as a result of the timing of revenue recognition, customer payments, maintenance contract renewals, contractual billing rights and maintenance revenue deferrals included in multiple element arrangements.

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We expect that our total revenue in 2024 will increase compared to our 2023 total revenue as our IP Optical sales continue to grow. From a regional perspective, we anticipate continued IP Optical revenue growth in 2024 from North America, Europe, the Middle East and Africa, and Central and Latin America. In the Cloud & Edge segment, we anticipate continued growth in Enterprise including U.S. Federal agencies, offsetting lower spending from U.S. service providers.

Cost of Revenue/Gross Margin. Our cost of revenue consists primarily of amounts paid to third-party manufacturers for purchased materials and services, royalties, amortization of acquired technology, inventory valuation adjustments, warranty costs, and manufacturing and services personnel and related costs. Our cost of revenue, gross profit and gross margin for the years ended December 31, 2023 and 2022 were as follows (in thousands, except percentages):

Our segment cost of revenue, gross profit and gross margin for the years ended December 31, 2023 and 2022 were as follows (in thousands, except percentages):

Our gross margin was slightly higher with a 0.5 percentage point increase in 2023 compared to 2022. This increase was the result of higher margins in both of our segments. The higher margin in our IP Optical segment was due to higher sales volume, favorable mix, lower product costs and royalties, and improved absorption of fixed costs from higher sales. The higher margin in our Cloud and Edge segment was primarily attributable to favorable product mix and lower product costs, including lower amortization of acquired technology costs.

We believe that our IP Optical Networks segment gross margin will improve in 2024 compared to 2023. Our overall consolidated gross margin may decrease in 2024 as a result of higher expected sales from IP Optical Networks, which has lower margins due to the higher hardware content in its products and higher production costs.

Research and Development. Research and development ("R&D") expenses consist primarily of salaries and related personnel expenses and prototype costs for the design, development, testing and enhancement of our products. R&D expenses for the years ended December 31, 2023 and 2022 were as follows (in thousands, except percentages):

The decrease in our research and development expenses in 2023 compared to 2022 was primarily attributable to approximately $8 million of lower expenses in our IP Optical Networks segment and approximately $5 million of lower expenses in our Cloud and Edge segment. The reduced expenses are a combination of lower employee headcount and outside subcontractors.

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Our IP Optical Networks R&D investment is focused on significantly expanding our portfolio of IP Routing solutions, adding additional features and capabilities to our Optical Transport portfolio, and supporting features in our next generation SDN management and orchestration platform.

Some aspects of our R&D efforts require significant short-term expenditures, the timing of which may cause significant variability in our expenses. We believe that rapid technological innovation is critical to our long-term success, and we are tailoring our investments to meet the requirements of our customers and market. We believe that our R&D expenses will continue to decrease modestly in 2024, with reduced investment in both segments in areas such as sustaining engineering, as well as a full year benefit of the cost savings implemented in the 2023 Restructuring Plan.

Sales and Marketing. Sales and marketing expenses consist primarily of salaries and related personnel costs, commissions, travel and entertainment expenses, promotions, customer trial and evaluations inventory and other marketing and sales support expenses. Sales and marketing expenses for the years ended December 31, 2023 and 2022 were as follows (in thousands, except percentages):

The decrease in sales and marketing expenses in 2023 compared to 2022 was primarily a result of a global sales organization re-alignment that reduced management layers, as well as reduced investment in under-performing regions. In the year 2023 compared to 2022, this resulted in a reduction of expenses of approximately $7 million in our IP Optical Networks segment and approximately $3 million in our Cloud & Edge segment.

We believe that our sales and marketing expenses will be modestly lower in 2024 compared to 2023 as we continue to benefit from the realigned global sales structure and continue to implement additional efficiencies.

General and Administrative. General and administrative expenses consist primarily of salaries and related personnel costs for executive and administrative personnel, and audit, legal and other professional fees. General and administrative expenses for the years ended December 31, 2023 and 2022 were as follows (in thousands, except percentages):

The increase in general and administrative expenses in 2023 compared to 2022 was primarily attributable to higher stock-based and other incentive compensation.

We believe that our general and administrative expenses in 2024 will increase slightly compared to our 2023 levels, primarily due to higher employee costs and as a result of inflation.

Amortization of Acquired Intangible Assets included in Operating expenses. Amortization of acquired intangible assets included in Operating expenses ("Opex Amortization") for the years ended December 31, 2023 and 2022 was as follows (in thousands, except percentages):

Opex Amortization was lower in 2023 compared to 2022 due to our method of amortization. We record our amortization in relation to expected future cash flows rather than on a straight-line basis. Accordingly, such expense may vary from one period to the next.

Acquisition-, Disposal- and Integration-Related. Acquisition-, disposal- and integration-related expenses include those expenses related to acquisitions that we would otherwise not have incurred. Acquisition- and disposal-related expenses include professional and services fees, such as legal, audit, consulting, paying agent and other fees. Integration-related expenses

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represent incremental costs related to combining our systems and processes with those of acquired businesses, such as third-party consulting and other third-party services.

We recorded $4.5 million of acquisition-, disposal- and integration-related expenses in 2023 compared to $6.3 million in 2022. These costs were related to integration following the ECI Acquisition and included license fees for systems in the process of being retired.

Restructuring and Related. We are committed to streamlining operations and reducing operating costs by closing and consolidating certain facilities and reducing our worldwide workforce. Please see the additional discussion of our restructuring initiatives in the "Restructuring and Cost Reduction Initiatives" section of the Overview of this MD&A.

We recorded restructuring and related expense of $16.2 million in 2023, comprised of $9.9 million for severance and related costs, and $6.3 million for variable and other facilities-related costs, including $1.0 million of net expense for the accelerated amortization of lease assets. We recorded $10.8 million of restructuring and related expense in 2022, comprised of $5.3 million for severance and related costs, and $5.5 million for variable and other facilities-related costs, including $1.6 million of net expense for the accelerated amortization of lease assets. Although we have eliminated positions as part of our restructuring initiatives, we continue to hire in certain areas that we believe are important to our future growth.

Interest Expense, net. Interest expense and interest income for the years ended December 31, 2023 and 2022 were as follows (in millions, except percentages):

Interest income was nominal in 2023. Interest expense in 2023 was primarily comprised of costs related to the 2020 Credit Facility (as defined below), consisting of $25.5 million of interest on our term loan and revolver, $3.2 million of amortization of debt issuance costs, $0.5 million of which related to the March 2023 Sixth Amendment to the 2020 Credit Facility. We also incurred $4.3 million of fees related to factoring certain accounts receivable. Our interest expense, amortization of debt issuance costs, and factoring fees were partially offset by $5.6 million of amortization of gains in Accumulated other comprehensive income from the sales of our interest rate swap. Our interest expense for the years ended December 31, 2023 and 2022 benefited from our interest rate swap, which was sold in March 2023. See Note 14 to our consolidated financial statements.

Interest income was nominal in 2022. Interest expense in 2022 was primarily comprised of $16.0 million of interest on our outstanding term debt, $2.3 million in the aggregate related to amortization of debt issuance costs in connection with the 2020 Credit Facility (as defined below) and $1.7 million primarily related to factoring certain accounts receivable.

Other (Expense) Income, Net. We recorded other expense, net, aggregating $3.8 million in 2023, primarily comprised of the $5.3 million fair value adjustment of our Preferred Stock and Warrants, including dividends on the Preferred Stock, and $3.5 million of costs incurred in the Private Placement, partially offset by the gain of $7.3 million recognized from Accumulated other comprehensive income in connection with the sale of our interest rate swap. We recorded other expense, net of $44.5 million in 2022, primarily comprised of $41.3 million of losses resulting from the change in the fair value of the AVCT Investment.

Income Taxes. We recorded an income tax provision of $10.8 million and income tax benefit of $14.5 million in 2023 and 2022, respectively. The change from a tax benefit in 2022 to a tax provision in 2023 is a result of changes in the jurisdictional mix of pre-tax book income between those jurisdictions that have a valuation allowance and those that do not.

During 2023 and 2022, we performed an analysis to determine if, based on all available evidence, we considered it more likely than not that some portion or all of the recorded deferred tax assets will not be realized in a future period. As a result of our evaluations, in 2023, for the U.S. deferred tax assets, we concluded that deferred tax assets are generally realizable, with the exception of certain federal and state net operating loss carryforwards, as well as certain tax credits, that are not anticipated to be utilized. Accordingly, we have maintained a valuation allowance on our U.S. deferred tax assets of $23.9 million. As a result of our evaluations for Israel, we maintained a full valuation allowance against our net deferred tax assets in Israel.

The Organization for Economic Cooperation and Development (the "OECD") Pillar 2 global minimum tax rules are

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intended to apply for tax years beginning in 2024. On February 1, 2023, the FASB staff noted that they believe that the Pillar 2 tax would be an alternative minimum tax and therefore deferred tax assets would not need to be recognized related to this parallel taxing system. On February 2, 2023, the OECD issued administrative guidance providing transition and safe harbor rules around the implementation of the Pillar 2 global minimum tax. Under an additional transitional safe harbor released July 17, 2023, the undertaxed profits rule top-up tax will not be applied by any constituent entity's jurisdiction of residence with respect to income earned by a company's ultimate parent entity in its jurisdiction of residence, if the ultimate parent entity's jurisdiction has a corporate tax rate of at least 20%. This transition safe harbor will apply to fiscal years beginning on or before December 31, 2025 and ending before December 31, 2026. We are closely monitoring developments and evaluating the impacts these new rules will have on our tax rate, including eligibility to qualify for these safe harbor rules and do not expect Pillar 2 to have a significant impact on our financial statements.

Years Ended December 31, 2022 and 2021

For a comparison of our results of operations for the fiscal years ended December 31, 2022 and 2021, see "Part II, Item 7. MD&A" of our Annual Report on Form 10-K for the year ended December 31, 2022, filed with the SEC on March 31, 2023.

Off-Balance Sheet Arrangements

We have no off-balance sheet arrangements that have or are reasonably likely to have a current or future material effect on our financial position, changes in financial position, revenue or expenses, results of operations, liquidity, capital expenditures or capital resources.

Liquidity and Capital Resources

Our consolidated statements of cash flows are summarized as follows (in thousands):

We had cash and cash equivalents aggregating $27 million and $67 million at December 31, 2023 and 2022, respectively. We had cash held by our non-U.S. subsidiaries aggregating approximately $16 million and $15 million at December 31, 2023 and 2022, respectively. If we elect to repatriate all of the funds held by our non-U.S. subsidiaries as of December 31, 2023, we do not believe that the amounts of potential withholding taxes that would arise from the repatriation would have a material effect on our liquidity.

We currently maintain the Senior Secured Credit Facilities Credit Agreement (as amended, the "2020 Credit Facility"), which we entered into on March 3, 2020, by and among us, as a guarantor, Ribbon Communications Operating Company, Inc., as the borrower ("Borrower"), Citizens Bank, N.A. ("Citizens"), Santander Bank, N.A., and others as lenders, ("Lenders"). For additional details regarding the terms of the 2020 Credit Facility, see Note 14 to our consolidated financial statements.

On March 10, 2022, we entered into the Fourth Amendment to the 2020 Credit Facility to increase the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility) and in conjunction we made a $15.0 million prepayment that was applied to the final payment due on the maturity date.

On June 30, 2022, we entered into the Fifth Amendment to the 2020 Credit Facility (the "Fifth Amendment") to increase the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility) for 2022, with the fourth quarter of 2022 increased to 4.75:1.00. In the first and second quarters of 2023, the Maximum Consolidated Net Leverage Ratio allowed declined to 3.25:1.00 and in all subsequent quarters the ratio will be fixed at 3.00:1.00. Also, the Fifth Amendment reduced the minimum Consolidated Fixed Charge Coverage Ratio (as defined in the 2020 Credit Facility) in 2022, with the fourth quarter of 2022 reduced to 1.10:1.00 and in all subsequent quarters the ratio will be fixed at 1.25:1.00. In addition, the Fifth Amendment increased the maximum rate at which loans bear interest if our Consolidated Net Leverage Ratio for any quarter is greater than 4.50:1.00. Specifically, loans incurred were to bear interest, at our option, at either LIBOR plus a margin ranging from 1.50% to 4.50% per year, or the base rate plus 0.50%, or the prime rate plus a margin ranging from 0.50% to 3.50% per year. The Fifth

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Amendment allowed us to incur junior secured or unsecured debt in an amount no less than $50 million, subject to certain conditions, including the requirement that 50% of the aggregate amount of such incurred debt (net of certain costs, fees and other amounts) must be applied to prepay the 2020 Credit Facility, and compliance with certain leverage ratio-based covenant exceptions. In connection with the Fifth Amendment, we made a $10.0 million voluntary prepayment that was applied to the final payment due on the maturity date. Subsequent to the Fifth Amendment, we are required to make quarterly principal payments on the 2020 Term Loan aggregating approximately $5.0 million per quarter through March 31, 2024 and $10.0 million in each of the three quarters thereafter, with the final payment due on the maturity date in March 2025.

On March 24, 2023, we entered into the Sixth Amendment to the 2020 Credit Facility (the “Sixth Amendment”) that was effective March 30, 2023. The Sixth Amendment, among other things, increased the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility), with the first, second and third quarters of 2023 increasing to 4.50:1.00 and then decreasing to 4.25:1.00 and 4.00:1.00 in the fourth quarter of 2023 and the first quarter of 2024, respectively. In all subsequent quarters, the Maximum Consolidated Senior Net Leverage Ratio will be fixed at 3.00:1.00 and the Maximum Consolidated Net Leverage Ratio will be fixed at 4.00:1.00. Also, the Sixth Amendment reduced the minimum Consolidated Fixed Charge Coverage Ratio (as defined in the 2020 Credit Facility) to 1.10:1.00 through the first quarter of 2024 and in all subsequent quarters the ratio will be fixed at 1.25:1.00. The Sixth Amendment reduced the maximum borrowings allowed under the 2020 Revolving Credit Facility from $100 million to $75 million and the sublimit available for letters of credit was reduced from $30 million to $20 million. In addition, the Sixth Amendment replaced LIBOR with the Secured Overnight Financing Rate ("SOFR") as the alternative rate that may be used by us for calculating interest owed under the 2020 Credit Facility, with the margin now fixed at 4.5%. In conjunction with the Sixth Amendment, we made a $75 million prepayment that was applied to the final payment due upon maturity in March 2025 of approximately $200.3 million. The $75 million prepayment was almost entirely funded with the net proceeds from the Private Placement and the sales of our interest rate swap. Debt issuance costs associated with the Sixth Amendment totaled $1.7 million and are being amortized on a straight-line basis over the remaining life of the 2020 Credit Facility to Interest expense, net.

At December 31, 2023, we had an outstanding balance under the 2020 Term Loan of $235.4 million at an average interest rate of 10.0% and $2.7 million of letters of credit outstanding with an interest rate of 4.5%. At December 31, 2022, we had an outstanding balance under the 2020 Term Loan of $330.4 million at an average interest rate of 5.4% and $3.3 million of letters of credit outstanding with an interest rate of 4.5%. Our interest rates under our 2020 Term Loan benefited from a hedge instrument that was in place, specifically a fixed rate swap, until the instrument was sold in March 2023 (see Note 15). We were in compliance with all covenants of the 2020 Credit Facility at both December 31, 2023 and 2022, including the current Consolidated Net Leverage Ratio calculation that considers our debt to include Preferred Stock.

We use letters of credit, bank guarantees, and performance and bid bonds in the course of our business. At December 31, 2023, we had $7.9 million of letters of credit, bank guarantees, and performance and bid bonds outstanding (collectively, "Guarantees"), comprised of $2.7 million of letters of credit under the 2020 Credit Facility described above (the "Letters of Credit") and $5.2 million of bank guarantees and performance and bid bonds (collectively, the "Other Guarantees"). At December 31, 2022, we had $8.3 million of Guarantees, comprised of the $3.3 million of Letters of Credit and $5.0 million of Other Guarantees.

We are exposed to financial market risk related to foreign currency fluctuations and changes in interest rates. These exposures are actively monitored by management. To manage the volatility related to the exposure to changes in interest rates, we may enter into a derivative financial instrument. Management's objective has been to reduce, where it is deemed appropriate to do so, fluctuations in earnings and cash flows associated with changes in interest rates. Our policies and practices are to use derivative financial instruments only to the extent necessary to manage exposures. We do not hold or issue derivative financial instruments for trading or speculative purposes.

As a result of exposure to interest rate movements, during March 2020, we entered into an interest rate swap arrangement, which effectively converted our $400 million term loan with its variable interest rate based upon one-month LIBOR to an aggregate fixed rate of 0.904%, plus a leverage-based margin as defined in the 2020 Credit Facility. The swap was to mature on March 3, 2025, the same date the 2020 Credit Facility matures. On July 22, 2022, we sold $30 million of the notional amount of our interest rate swap back to our counterparty for $1.5 million, reducing the notional amount of this swap to $370 million. On August 16, 2022, we sold another $30 million of the notional amount of our interest rate swap back to our counterparty for $1.6 million, reducing the notional amount to $340 million, which approximated the term loan debt then outstanding. The gain in Accumulated other comprehensive income related to the $60 million notional amount sold of $3.1 million is being released into earnings on a straight-line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense, the amortization of which totaled $0.9 million for the year ended December 31, 2023. On March 24, 2023, we received $9.4 million, consisting of $0.4 million of interest and $9.0 million for the sale of $170 million of the $340 million notional amount of our interest rate swap back to our counterparty, reducing the notional amount to $170 million. On March 27,

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2023, we received $9.8 million, consisting of $0.4 million of interest and $9.4 million for the sale of the remaining $170 million of our interest rate swap back to our counterparty. The portion of the gain in Accumulated other comprehensive income related to the term loan debt prepaid on the date of the final sale of our swap totaled $7.3 million and was released into earnings immediately as Other expense, net. The portion of the gain in Accumulated other comprehensive income related to our remaining term loan debt balance totaled $12.0 million and is being released into earnings on a straight-line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense, the amortization of which was $4.7 million for the year ended December 31, 2023.

Our objectives in using interest rate derivatives have been to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we have used an interest rate swap as part of our interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for making fixed-rate payments over the life of an agreement without exchange of the underlying notional amount.

The effective portion of changes in the fair value of designated derivatives that qualify as cash flow hedges is recorded in Accumulated other comprehensive income in the consolidated balance sheet and is subsequently reclassified into earnings in the period that the hedged forecasted transactions affect earnings. During the years ended December 31, 2023 and 2022, such a derivative was used to hedge the variable cash flows associated with the outstanding borrowings under the 2020 Credit Facility and we have accounted for this derivative as an effective hedge until the final portion of the swap was sold on March 27, 2023. Any ineffective portion of the change in fair value of the derivative was recognized directly in earnings. However, during the years ended December 31, 2023, 2022 and 2021, we recorded no hedge ineffectiveness. In the year ended December 31, 2023, we recorded $7.3 million of Other expense, net due to the sale of our interest rate swap arrangement.

Cash Flows from Operating Activities

Our primary source of cash from operating activities has been from cash collections from our customers. We expect cash flows from operating activities to be affected by increases and decreases in sales volumes and timing of collections, and by purchases and shipments of inventory. Our primary uses of cash from operating activities have been for personnel costs and investment in our research and development and in our sales and marketing, and general and administrative departments.

Our operating activities provided $17 million of cash in 2023, primarily resulting from our net loss, which was more than offset by certain non-cash expenses, such as amortization of intangible assets, stock-based compensation, depreciation and amortization of property and equipment, amortization of debt issuance costs and the change in the fair value of our preferred stock and warrant liabilities, including dividends on our preferred stock, partially offset by deferred income taxes and the gain on the sale of our interest rate swap. Also, the changes in our operating assets and liabilities provided operating cash, including lower other operating assets and accounts receivable, partially offset by lower accrued expenses and other long-term liabilities, higher inventory, and lower accounts payable. Higher product revenue in our IP Optical Networks segment and lower operating expenses company-wide due to our various cost saving initiatives, including lower employee and facilities expenses, have all positively affected our operating cash flow in 2023.

Our operating activities used $26 million of cash in 2022, primarily resulting from our net loss, lower accrued expenses and other long-term liabilities, and higher inventory. The decrease in accrued expenses and other long-term liabilities was primarily due to employee-related cash payments and payments related to facilities, professional fees and royalties. These amounts were partially offset by certain non-cash expenses, such as amortization of intangible assets, the decrease in the fair value of the AVCT Investment, stock-based compensation, as well as depreciation and amortization of property and equipment.

Cash Flows from Investing Activities

Our investing activities used $9 million and $12 million of cash in 2023 and 2022, respectively. Our 2023 investing activities were used to purchase property and equipment and software licenses. Our 2022 investing activities were comprised of $10 million paid for purchases of property and equipment, and $3 million paid for purchases of software licenses, partially offset by $1 million of proceeds from the sale of a business.

Cash Flows from Financing Activities

Our financing activities used $48 million of cash in 2023, primarily due to $95 million of principal payments on our term debt, including a $75 million prepayment in connection with the Sixth Amendment to the 2020 Credit Facility, $2 million of debt issuance costs also paid in connection with the Sixth Amendment, and $4 million for the payment of tax withholding

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related to the net share settlements of restricted stock awards upon vesting. In addition, we received $53 million of proceeds from the issuance of the Preferred Stock and Warrants in the Private Placement.

Our financing activities provided $1 million of cash in 2022, primarily due to $50 million of net proceeds from the private placement by us of 17,071,311 shares of our common stock, par value $0.0001 per share, at a price of $3.05 per share on August 12, 2022 (the "Equity Offering"), partially offset by $45 million of principal payments on the 2020 Credit Facility, including the voluntary $15 million incremental principal payment in connection with the Fourth Amendment and voluntary $10 million incremental principal payment in connection with the Fifth Amendment, and $3 million for the payment of tax withholding obligations related to the net share settlements of restricted stock awards upon vesting. Payments of debt issuance costs and principal payments of finance leases together totaled approximately $2 million.

Based on our current expectations, we believe our current cash balance, the cash generated from our operations, and borrowings available under the 2020 Credit Facility, will be sufficient to meet our anticipated cash needs for working capital and capital expenditures for at least twelve months from the date of issuance of these financial statements. The rate at which we consume cash is dependent on the cash needs of our future operations, including our contractual obligations at December 31, 2023, primarily comprised of our debt principal and interest obligations as described above, and our operating lease and purchase obligations. Our operating lease obligations totaled $65 million at December 31, 2023, with payments aggregating $19 million in 2024, $10 million in 2025, $9 million in 2026 and $27 million thereafter. Our purchase obligations totaled $114 million at December 31, 2023, with estimated payments aggregating $101 million in 2024 and $13 million thereafter. We anticipate devoting substantial capital resources to continue our research and development efforts, to maintain our sales, support and marketing, and for other general corporate activities. We further believe that our financial resources, along with managing discretionary expenses, will allow us to manage the ongoing impact of inflation and the supply chain disruptions on our business operations. Looking ahead, we have developed contingency plans to reduce costs further if the situation deteriorates. However, it is difficult to predict future liquidity requirements with certainty, and our cash and available borrowings under the 2020 Credit Facility may not be sufficient to meet our future needs, which would require us to refinance our debt and/or obtain additional financing. We may not be able to refinance our debt or obtain additional financing on favorable terms or at all.

Recent Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (the "FASB") issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which increases the disclosure requirements around rate reconciliation information and certain types of income taxes companies are required to pay. ASU 2023-09 will be effective for us beginning in 2025, with early adoption permitted. We are currently evaluating the impact of this accounting standard update on our consolidated financial statements and related disclosures.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which improves reportable segment disclosure requirements, including enhancement of the disclosures of significant segment expenses and interim disclosure requirements, to enable investors to better understand an entity's overall performance and assess potential future cash flows. ASU 2023-07 will be effective for us annually beginning in 2024 and on an interim basis beginning in 2025, with early adoption permitted. We are currently evaluating the impact of this accounting standard update on our consolidated financial statements and related disclosures.

In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC's disclosure Update and Simplification Initiative (“ASU 2023-06”), which amends the disclosure or presentation requirements related to various subtopics in the FASB Accounting Standards Codification. This ASU was issued in response to and to align GAAP with the SEC's August 2018 final rule that updates and simplifies disclosure requirements. The effective date for us for each amendment will be the date on which the SEC's removal of that related disclosure requirement becomes effective, with early adoption prohibited. We are currently evaluating the impact of this accounting standard update on our consolidated financial statements and related disclosures.

On February 1, 2023, the FASB staff noted that they believe that the Pillar 2 tax, established by the OECD and intended to apply for tax years beginning in 2024, would be an alternative minimum tax and therefore deferred tax assets would not need to be recognized related to this parallel taxing system. On February 2, 2023, the OECD issued administrative guidance providing transition and safe harbor rules around the implementation of the Pillar 2 global minimum tax. Under an additional transitional safe harbor released July 17, 2023, the undertaxed profits rule top-up tax will not be applied by any constituent entity's jurisdiction of residence with respect to income earned by a company's ultimate parent entity in its jurisdiction of residence, if the ultimate parent entity's jurisdiction has a corporate tax rate of at least 20%. This transition safe harbor will apply to fiscal years beginning on or before December 31, 2025 and ending before December 31, 2026. We are closely monitoring developments and evaluating the impacts these new rules will have on our tax rate, including eligibility to qualify for these safe

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harbor rules. Based upon preliminary calculations for calendar year 2024, we anticipate that we will meet the safe harbors in most jurisdictions, and any remaining top-up tax should be immaterial.

In March 2022, the Financial Accounting Standards Board (the "FASB") issued ASU 2022-02, Financial Instruments – Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures (“ASU 2022-02”), which eliminates the accounting guidance on troubled debt restructurings for creditors in ASC 310, Receivables (Topic 310), and requires entities to provide disclosures about current period gross write-offs by year of origination. Also, ASU 2022-02 updates the requirements related to accounting for credit losses under ASC 326, Financial Instruments – Credit Losses (Topic 326), and adds enhanced disclosures for creditors with respect to loan refinancings and restructurings for borrowers experiencing financial difficulty. ASU 2022-02 became effective for us January 1, 2023. The adoption of ASU 2022-02 did not have a material impact on our consolidated financial statements upon adoption.

In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers ("ASU 2021-08"), which amends ASC 805, Business Combinations (Topic 805), to add contract assets and contract liabilities to the list of exceptions to the recognition and measurement principles that apply to business combinations and to require that an acquiring entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with ASC 606, Revenue from Contracts with Customers (Topic 606) ("ASC 606"). Under current GAAP, an acquirer generally recognizes such items at fair value on the acquisition date. While primarily related to contract assets and contract liabilities that were accounted for by the acquiree in accordance with ASC 606, ASU 2021-08 also applies to contract assets and contract liabilities from other contracts to which the provisions of ASC 606 apply, such as contract liabilities from the sale of nonfinancial assets within the scope of ASU 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20). ASU 2021-08 was effective for us January 1, 2023. We believe the adoption of ASU 2021-08 could have a material impact on our consolidated financial statements for periods including and subsequent to significant business acquisitions.

Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with our financial statements and the related notes included in Item 8, "Financial Statements and Supplementary Data” in this Annual Report on Form 10-K. This discussion contains forward-looking statements that reflect our plans, estimates and beliefs and involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of various factors including, but not limited to, those disclosed in Item 1A, “Risk Factors”, elsewhere in this Annual Report on Form 10-K, in other documents filed with the SEC and otherwise publicly disclosed. Please refer to “Cautionary Note Regarding Forward-Looking Statements” above for additional information. For a complete description of our business and other important information, please refer to Item 1 of Part I of this Annual Report on Form 10-K.

Overview

We are a leading global provider of communications technology to service providers and enterprises. We provide a broad range of software and high-performance hardware products, solutions and services that enable the secure delivery of data and voice communications for residential consumers and for small, medium and large enterprises and industry verticals such as finance, education, government, utilities and transportation. Our mission is to create a recognized global technology leader providing cloud-centric solutions that enable the secure exchange of information, with unparalleled scale, performance and elasticity. Headquartered in Plano, Texas, we have a global presence with research and development and/or sales and support locations in over thirty countries around the world.

Key Trends and Economic Factors Affecting Ribbon

COVID-19 and Supplier Disruptions. The ongoing COVID-19 pandemic has had a negative effect on the global economy, disrupting the various manufacturing, commodity and financial markets and increasing volatility, and has impeded global supply chains. Our ability to deliver our solutions as agreed upon with our customers depends in part on the ability of our global contract manufacturers, vendors, licensors and other business partners to deliver products or perform services we have procured from them.

The Ongoing Military Conflict in Ukraine. The uncertainty resulting from the military conflict in Ukraine and the threat for expansion of the conflict has resulted in some of our customers delaying purchases from us. Further, the U.S. and other European countries have imposed sanctions against Russia in connection with the conflict. These sanctions currently prohibit our ability to sell certain products and services. The sanctions continue to evolve and further changes in the current sanctions could further limit our ability to sell products and services to customers in Russia and, our ability to collect on outstanding accounts receivable from such customers. If we are further limited in our ability to sell products and services to Russia and other countries for an extended period, it could have a material impact on our financial results.

Inflation and Interest Rates. We continue to see near-term impacts on our business due to inflation, including ongoing global price pressures, driving up energy prices, component costs, freight premiums, and other operating costs above normal rates. Although headline inflation in the United States and Europe appears to have peaked, as gasoline and natural gas prices recede from the latest spike, core inflation (excluding food and energy prices) remains elevated and is a source of continued cost pressure on businesses and households. Interest rates have increased significantly as central banks in developed countries attempt to subdue inflation while government deficits and debt remain at high levels in many global markets. Accordingly, the eventual implications of higher government deficits and debt, tighter monetary policy, and potentially higher long-term interest rates may drive a higher cost of capital for our business.

Continued uncertain global economic conditions, including as a result of the ongoing COVID-19 pandemic, the ongoing military conflict in Ukraine and the high inflationary and rising interest environment, may cause our customers to restrict spending or delay purchases for an indeterminate period of time and consequently cause our revenues to decline. Further, such factors may negatively impact our operating costs resulting in a reduction in net income. The degree to which the ongoing COVID-19 pandemic, the ongoing military conflict in Ukraine and the high inflationary and rising interest rate environment impacts our future business, financial position and results of operations will depend on developments beyond our control, including the duration of the global economic downturn that has resulted from these factors.

Presentation

Unless otherwise noted, all financial amounts, excluding tabular information, in this Management's Discussion and Analysis of Financial Condition and Results of Operations ("MD&A") are rounded to the nearest million dollar amount, and all

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percentages, excluding tabular information, are rounded to the nearest percentage point.

Equity Offering

On August 12, 2022, we entered into a Securities Purchase Agreement with certain investors for the sale (the "Equity Offering") in a private placement by us of 17,071,311 shares (the "Shares") of our common stock, par value $0.0001 per share, at a price of $3.05 per share. The aggregate gross proceeds from the Equity Offering were approximately $52.1 million, including $10 million from existing related party shareholders, before deducting offering expenses paid by us of approximately $1.7 million. We intend to continue to use the net proceeds from the Equity Offering to fund general corporate purposes, including capital expenditures, working capital and repayment of debt.

The original issuance of the Shares in the Equity Offering was exempt from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”) pursuant to Section 4(a)(2) or Regulation D promulgated thereunder. The Company subsequently filed a registration statement on Form S-3 (the “Registration Statement”) with the SEC registering the Shares, which Registration Statement was declared effective by the SEC on September 23, 2022.

2022 Restructuring Initiative

On February 14, 2022, our Board of Directors approved a strategic restructuring program (the "2022 Restructuring Plan") to streamline the Company's operations in order to support the Company's investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements.

We recorded approximately $10.2 million of restructuring and related expense in 2022 associated with the 2022 Restructuring Plan, including approximately $5.3 million related to employee severance arrangements and approximately $4.9 million related to the facilities consolidation, including $1.6 million of net expense related to the accelerated amortization of leased assets. We anticipate that we will record future expense aggregating approximately $8 million in connection with the 2022 Restructuring Plan which will be completed by the end of 2023.

Business Acquisitions

ECI Telecom Group Ltd.

On March 3, 2020 (the "ECI Acquisition Date"), we completed the acquisition of ECI Telecom Group Ltd. ("ECI") in accordance with the terms of the Agreement and Plan of Merger, dated as of November 14, 2019, by and among Ribbon, an indirect wholly-owned subsidiary of Ribbon ("Merger Sub"), Ribbon Communications Israel Ltd., ECI, and ECI Holding (Hungary) Kft, pursuant to which Merger Sub merged with and into ECI, with ECI surviving such merger as a wholly-owned subsidiary of Ribbon (the "ECI Acquisition"). Prior to the ECI Acquisition Date, ECI was a privately-held global provider of end-to-end packet-optical transport and software-defined networking ("SDN") and network function virtualization ("NFV") solutions for service providers, enterprises and data center operators. Ribbon believes the ECI Acquisition positions the Company for growth and enhances its competitive strengths by expanding its product portfolio beyond solutions primarily supporting voice applications to include data applications and optical networking.

As consideration for the ECI Acquisition, we issued the ECI shareholders and certain others 32.5 million shares of Ribbon common stock with a fair value of $108.6 million (the "Stock Consideration") and paid $322.5 million of cash, comprised of $183.3 million to repay ECI's outstanding debt, including both principal and interest, and $139.2 million paid to ECI's selling shareholders (the "Cash Consideration"). In addition, ECI shareholders received $33.4 million from the sale of certain of ECI's real estate assets. Cash Consideration was financed through cash on hand and committed debt financing consisting of a new $400 million term loan facility and new $100 million revolving credit facility, which was undrawn at the ECI Acquisition Date. The ECI Acquisition has been accounted for as a business combination and the financial results of ECI have been included in our consolidated financial statements for the periods subsequent to the ECI Acquisition Date.

Sale of Kandy Communications Business and Investment in AVCT

On December 1, 2020 (the "Kandy Sale Date"), we completed the sale of our Kandy Communications Business to American Virtual Cloud Technologies, Inc. ("AVCT"). AVCT purchased the assets and assumed certain liabilities associated with the Kandy Communications Business, as well as all of the outstanding interests in Kandy Communications LLC, our subsidiary (the "Kandy Sale"). The assets acquired and liabilities assumed by AVCT in connection with the Kandy Sale were primarily comprised of accounts receivable, property and equipment, trade accounts payable and employee-related accruals.

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As consideration, AVCT paid us $45.0 million, subject to certain adjustments, in the form of units of AVCT's securities (the "AVCT Units"), with each AVCT Unit consisting of: $1,000 in principal amount of AVCT’s Series A-1 convertible debentures (the “Debentures”); and (ii) one warrant to purchase 100 shares of AVCT common stock, $0.0001 par value (the “Warrants”), as consideration for the Kandy Sale. We received 43,778 AVCT Units as consideration on the Kandy Sale Date.

The Debentures bore interest at a rate of 10% per annum, which was being added to the principal amount of the Debentures. The entire principal amount of each Debenture, together with accrued and unpaid interest thereon, was due and payable on the earlier of the May 1, 2023 maturity date or the occurrence of a Change in Control as defined in the definitive purchase agreement, as amended (the "Amended Kandy Agreement"). Each Debenture was convertible, in whole or in part, at any time at our option into that number of shares of AVCT common stock, calculated by dividing the principal amount being converted, together with all accrued and unpaid interest thereon, by the applicable conversion price, which initially per share was $3.45. The Debentures were subject to mandatory conversion if the AVCT stock price was at or above $6.00 per share for 40 trading days in any 60 consecutive trading day period, subject to the satisfaction of certain other conditions. The conversion price was subject to customary adjustments including, but not limited to, stock dividends, stock splits and reclassifications. As of February 19, 2021, the stock price had traded above $6.00 for 40 days within a 60 consecutive trading day period, and accordingly, on September 8, 2021 (the "Debenture Conversion Date") upon the completion of customary regulatory filings by AVCT, the Debentures were converted into 13,700,421 shares of AVCT common stock (the "Debenture Shares").

The Warrants were independent of the Debentures and entitle us to purchase 4,377,800 shares of AVCT common stock at an exercise price of $0.01 per share. The Warrants were immediately exercisable on the Kandy Sale Date and expire on December 1, 2025. We had not exercised any of the Warrants as of December 31, 2021. We were also subject to a lock-up provision which limited our ability to sell any shares of the AVCT common stock underlying the AVCT Units prior to June 1, 2021 (the "Lock-Up Period"), except in certain transactions.

We determined that the AVCT Units had a fair value of $84.9 million at the Kandy Sale Date, comprised of the Debentures with a fair value of $66.3 million and the Warrants with a fair value of $18.6 million. The value of the net assets sold to AVCT totaled $1.3 million, resulting in a gain on the sale of $83.6 million. We calculated the fair value of the Debentures using a Lattice-based valuation approach, which utilizes a binomial tree to model the different paths the price of AVCT's common stock might take over the Debentures' life by using assumptions regarding the stock price volatility and risk-free interest rate. These results were then used to calculate the fair value of the Debentures at each measurement date prior to the Debenture Conversion Date. We used the Black-Scholes valuation model for estimating the fair value of the Warrants at each measurement date. The fair value of the Warrants was affected by AVCT's stock price as well as valuation assumptions, including the volatility of AVCT's stock price, expected term of the option, risk-free interest rate and expected dividends. Both the Lattice and Black-Scholes valuation models are based on available market data, giving consideration to all of the rights and obligations of each instrument and precluding the use of "blockage" discounts or premiums in determining the fair value of a large block of financial instruments. After the expiration of the Lock-Up Period and prior to the Debenture Conversion Date, we valued the AVCT Units at each measurement date by multiplying the closing stock price of AVCT common stock by the number of shares upon conversion of the Debentures and Warrants. At December 31, 2021, we valued the Debenture Shares and Warrants (the "AVCT Investment") by multiplying the closing stock price of AVCT common stock by the number of Debenture Shares and Warrants we held.

At December 31, 2021, the fair value of the AVCT Investment was $43.9 million, comprised of $33.3 million for the Debenture Shares and $10.6 million for the Warrants. We recorded a loss of $74.8 million in the year ended December 31, 2021 arising from the change in their aggregate fair value. This amount is included as a component of Other (expense) income, net, in our consolidated statement of operations. We recorded $3.5 million of interest income in the year ended December 31, 2021, respectively, which was added to the principal amount of the Debentures prior to the Debenture Conversion Date, and which is included in Interest expense, net, in our consolidated statement of operations. At December 31, 2020, the fair value of the AVCT Units was $115.2 million. The fair value of the AVCT Investment at December 31, 2021 and the AVCT Units at December 31, 2020 are reported as Investments in our consolidated balance sheets. The AVCT Investment is classified as a Level 1 fair value measurement at December 31, 2021 and the AVCT Units are classified as Level 2 fair value measurements within the fair value hierarchy at December 31, 2020.

We evaluated the nature of our investment in AVCT for the period from the Debenture Conversion Date through December 31, 2021 and determined that it represented an approximate 15% equity interest in AVCT on a diluted basis. Accordingly, we determined that we are not the primary beneficiary of AVCT as we do not have the power to direct the activities that most significantly impact the AVCT Investment's economic performance and therefore concluded that we had neither significant influence nor a controlling interest arising from the AVCT Investment.

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On August 29, 2022, the Company and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of the Company's investment in the Debenture Shares and the Warrants with an aggregate fair value of $2.6 million. Pursuant to the settlement agreements, the Company and AVCT also entered into a Wind Down Agreement, pursuant to which a Reseller Agreement between the parties, as previously amended, was terminated, and the Company was granted a non-exclusive perpetual license to use and modify certain intellectual property owned by AVCT comprising WebRTC gateway technology that is integrated with Ribbon’s SBCs and Application Servers. As consideration, the Company paid AVCT $2.5 million in cash, the Debenture Shares were redeemed and canceled, and the Warrants were terminated and canceled. The perpetual license granted by AVCT is classified as Intangible assets, net in the Company's consolidated balance sheet as of December 31, 2022 in the amount of $3.9 million.

Litigation Settlement

On April 22, 2019, we and Metaswitch Networks Ltd., Metaswitch Networks Corp and Metaswitch Inc. (collectively, "Metaswitch") agreed to a binding mediator's proposal that resolves the six previously disclosed lawsuits between the Company and Metaswitch (the "Lawsuits"). We and Metaswitch signed a Settlement and Cross-License Agreement on May 29, 2019 (the "Royalty Agreement"). Pursuant to the terms of the Royalty Agreement, Metaswitch agreed to pay us an aggregate amount of $63.0 million, which included cash payments of $37.5 million during the second quarter of 2019 and $25.5 million payable in three installments annually, beginning June 26, 2020, with such installment payments accruing interest at a rate of 4% per year. As part of the Royalty Agreement, we and Metaswitch have (i) released the other from all claims and liabilities; (ii) licensed each party's existing patent portfolio to the other party; and (iii) requested the applicable courts to dismiss the Lawsuits. We received $37.5 million of aggregate payments from Metaswitch in the second quarter of 2019 and recorded notes receivable for future payments of $25.5 million, comprised of $8.5 million in Other current assets and $17.0 million in Other assets in our consolidated balance sheet at December 31, 2019. We recorded the $63.0 million gain in Other (expense) income, net, in our consolidated statement of operations for the year ended December 31, 2019. We received $37.5 million of aggregate payments from Metaswitch in the second quarter of 2019 and $9.5 million, including $1.0 million of interest, in the second quarter of 2020.

On July 6, 2020, we and Metaswitch signed a First Supplemental Agreement to the Settlement and Cross-License Agreement (the "Supplemental Agreement") under which Metaswitch could elect to repay the outstanding amounts under the Royalty Agreement early in exchange for a reduction of $0.25 million to the outstanding principal, from $17.0 million to $16.75 million, and the payment of no further interest by Metaswitch effective June 26, 2020. We recorded the reduction to the outstanding principal as a reduction to interest income. On July 14, 2020, Metaswitch paid us the remaining outstanding balance of $16.75 million.

Operating Segments

Our chief operating decision maker (the "CODM") is our president and chief executive officer. Effective in the fourth quarter of 2020 and in connection with the ECI Acquisition, our CODM began to assess our performance based on the performance of two separate lines of business within Ribbon: the Cloud and Edge operating segment ("Cloud and Edge") and the IP Optical Networks operating segment ("IP Optical Networks"). We previously operated in a single segment, as our CODM made decisions and assessed performance at the company level, and for periods prior to the ECI Acquisition, there are no financial results for IP Optical Networks to report.

Our Cloud and Edge operating segment provides secure and reliable software and hardware products, solutions and services for Voice over Internet Protocol ("VoIP") communications, Voice over Long-Term Evolution ("VoLTE") and Voice Over 5G ("VoNR") communications, and Unified Communications and Collaboration ("UC&C") services to both service provider and enterprise customers. Our Cloud and Edge products are increasingly software-centric and cloud-native for deployment on private, public or hybrid cloud infrastructures, in data centers, on enterprise premises and within service provider networks. Our Cloud and Edge product portfolio consists of our Session Border Controller ("SBC") products and our Network Transformation ("NTR") products.

Our IP Optical Networks operating segment provides high-performance, secure solutions for IP networking and optical transport, supporting wireless networks including 5G, metro and edge aggregation, core networking, data center interconnect, legacy network transformation and transport solutions for wholesale carriers. This portfolio is offered to service provider, enterprise and industry verticals with critical transport network infrastructures including utilities, government, defense, transportation, and education and research.

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Financial Overview

Financial Results

We reported a loss from operations of $48.3 million for 2022 and $117.8 million for 2021. We reported a net loss of $98.1 million for 2022 and $177.2 million for 2021.

Our revenue was $819.8 million in 2022, comprised of $508.2 million attributable to Cloud and Edge and $311.6 million attributable to IP Optical Networks. Our revenue was $845.0 million in 2021, comprised of $556.7 million attributable to Cloud and Edge and $288.3 million attributable to IP Optical Networks. Our gross profit was $400.9 million in 2022, comprised of $310.3 million attributable to Cloud and Edge and $90.6 million attributable to IP Optical Networks. Our gross profit was $444.7 million in 2021, comprised of $343.5 million attributable to Cloud and Edge and $101.2 million attributable to IP Optical Networks. Our gross margin was 48.9% in 2022 and 52.6% in 2021. In 2022, our Cloud and Edge gross margin was 61.1% and our IP Optical Networks gross margin was 29.1%. In 2021, our Cloud and Edge gross margin was 61.7% and our IP Optical Networks gross margin was 35.1%.

Our operating expenses were $449.3 million in 2022 and $562.5 million in 2021. Our 2022 operating expenses included $29.6 million of amortization of acquired intangible assets, $6.3 million of acquisition-, disposal- and integration-related expense, and $10.8 million of restructuring and related expense. Our 2021 operating expenses included $116.0 million for the impairment of goodwill, $28.3 million of amortization of acquired intangible assets, $7.6 million of acquisition-, disposal- and integration-related expense, and $11.7 million of restructuring and related expense.

We recorded stock-based compensation expense of $18.7 million in 2022 and $19.4 million in 2021.

See "Results of Operations" in this MD&A for additional discussion of our results of operations for the years ended December 31, 2022 and 2021.

Restructuring and Cost Reduction Initiatives

In February 2022, our Board of Directors approved the 2022 Restructuring Plan to streamline the Company's operations in order to support the Company's investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with this initiative, we recorded restructuring and related expense of $10.2 million in 2022, comprised of $3.3 million for variable and other facilities-related costs, $1.6 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease, and $5.3 million for severance and related costs for approximately 70 employees. We anticipate that the 2022 Restructuring Plan will be completed by the end of 2023 and we will record future related expense of approximately $8 million.

In 2020, we implemented a restructuring plan to eliminate certain positions and redundant facilities, primarily in connection with the ECI Acquisition, to further streamline our global footprint and improve our operations (the "2020 Restructuring Initiative"). In connection with this initiative, we eliminated duplicate functions arising from the ECI Acquisition in support of our efforts to integrate the two companies. In connection with the 2020 Restructuring Initiative, we recorded a nominal amount of restructuring and related expense in 2022 and $4.7 million of such expense in 2021. The 2021 amount was comprised of $4.6 million for severance and related costs for approximately 60 employees and $0.1 million for variable and other facilities-related costs. All amounts will be fully paid in 2023. We expect to record nominal if any future restructuring and related expense under the 2020 Restructuring Initiative.

In 2019, we implemented a restructuring plan to streamline our global footprint, improve our operations and enhance our customer delivery (the "2019 Restructuring Initiative"). The 2019 Restructuring Initiative includes facility consolidations, refinement of our research and development activities, and a reduction in workforce. The facility consolidations under the 2019 Restructuring Initiative (the "Facilities Initiative") included a consolidation of our North Texas sites into a single campus, housing engineering, customer training and support, and administrative functions, as well as a reduction or elimination of certain excess and duplicative facilities worldwide. In addition, the Facilities initiative included consolidating our global software laboratories and server farms into two lower cost North American sites. We continue to evaluate our properties included in the Facilities Initiative for accelerated amortization and/or right-of-use asset impairment. We expect that the actions under the Facilities Initiative will be substantially completed in 2023.

In connection with the 2019 Restructuring Initiative, we recorded restructuring and related expense of $0.7 million in 2022 comprised entirely of facilities related expense. We recorded restructuring and related expense of $7.0 million in 2021,

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comprised of $5.7 million for variable and other facilities-related costs and $1.3 million of net expense for accelerated amortization of lease assets. The amount for accelerated amortization of lease assets was comprised of $3.4 million of expense and $2.1 million of income related to a lease modification for one of our restructured lease facilities. The amount accrued for severance and related costs was paid in 2021.

Accelerated rent amortization is recognized from the date that we commence the plan to fully or partially vacate a facility, for which there is no intent or ability to enter into a sublease, through the final vacate date. We recorded $1.6 million and $3.4 million of expense for accelerated rent amortization in the years ended December 31, 2022 and 2021, respectively. These amounts are included as components of Restructuring and related expense, and reduced our Operating lease right-of-use assets in our consolidated balance sheets at December 31, 2022 and 2021. We continue to evaluate our properties included in the Facilities Initiative for accelerated amortization and/or right-of-use asset impairment. We may incur additional future expense if we are unable to sublease other locations included in the Facilities Initiative.

Critical Accounting Policies and Estimates

This MD&A is based upon our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosure of contingent assets and liabilities. We base our estimates and judgments on historical experience, knowledge of current conditions and beliefs of what could occur in the future given available information. We consider the following accounting policies to be both those most important to the portrayal of our financial condition and those that require the most subjective judgment. If actual results differ significantly from management's estimates and projections, there could be a material effect on our consolidated financial statements. The significant accounting policies that we believe are the most critical include revenue recognition, the valuation of inventory, debentures and warrants received as sale consideration, warranty accruals, loss contingencies and reserves, stock-based compensation, business combinations, goodwill and intangible assets and accounting for income taxes.

Revenue Recognition. We derive revenue from two primary sources: products and services. Product revenue is generated from sales of our stand-alone software, as well as software with attached hardware that function together to deliver the products' essential functionality. Both software and hardware are also sold on a standalone basis. Services include customer support (software updates and technical support), consulting, design services, installation services and training. A typical contract includes both product and services. Generally, contracts with customers contain multiple performance obligations. For these contracts, we account for individual performance obligations separately if they are distinct. The transaction price is allocated to the separate performance obligations on a relative standalone selling price basis. SSPs are typically estimated using all observable transactions, including when products and services are sold on a standalone basis.

The software licenses typically provide a perpetual right to use our software. We also sell term-based software licenses that expire and Software-as-as-Service ("SaaS")-based software, which are referred to as subscription arrangements. We do not customize our software nor are installation services required, as the customer has a right to utilize internal resources or a third-party service company. The software and hardware are delivered before related services are provided and are functional without professional services or customer support. We have concluded that our software licenses are functional intellectual property that are distinct, as the user can benefit from the software on its own. The product revenue is typically recognized upon transfer of control or when the software is made available for download, as this is the point that the user of the software can direct the use of, and obtain substantially all of the remaining benefits from, the functional intellectual property. We begin to recognize software revenue related to the renewal of subscription software licenses at the start of the subscription period.

Service revenue includes revenue from customer support and other professional services. We offer warranties on our products. Certain of our warranties are considered to be assurance-type in nature, ensuring that the product is functioning as intended. Assurance-type warranties do not represent separate performance obligations. We also sell separately-priced maintenance service contracts which qualify as service-type warranties and represent separate performance obligations. We do not allow and have no history of accepting product returns.

Customer support includes software updates on a when-and-if-available basis, telephone support, integrated web-based support and bug fixes or patches. We sell our customer support contracts at a percentage of list or net product price related to the support. Customer support revenue is recognized ratably over the term of the customer support agreement, which is typically one year.

Our professional services include consulting, technical support, resident engineer services, design services and installation services. Because control transfers over time, revenue is recognized based on progress toward completion of the performance

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obligation. The method to measure progress toward completion requires judgment and is based on the nature of the products or services to be provided. We generally use the input method to measure progress for our contracts because we believe it best depicts the transfer of assets to the customer which occurs as we incur costs for the contracts. However, in some instances, we use the output method because it best depicts the transfer of asset to the customer. Under the cost-to-cost measure of progress, the progress toward completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. When the measure of progress is based upon expended labor, progress toward completion is measured as the ratio of labor time expended to date versus the total estimated labor time required to complete the performance obligation. Revenue is recorded proportionally as costs are incurred or as labor is expended. Costs to fulfill these obligations include internal labor as well as subcontractor costs.

We offer customer training courses, for which the related revenue is typically recognized as the training services are performed.

Our contracts with customers often include promises to transfer multiple products and services to the customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment.

Judgment is required to determine the SSP for each distinct performance obligation. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, the Company may use information such as the size of the customer and geographic region in determining the SSP.

Valuation of Inventory. We review inventory for both potential obsolescence and potential loss of value periodically. In this review, we make assumptions about the future demand for and market value of the inventory and, based on these assumptions, estimate the amount of any excess, obsolete or slow-moving inventory.

We write down our inventories if they are considered to be obsolete or at levels in excess of forecasted demand. In these cases, inventory is written down to estimated realizable value based on historical usage and expected demand. Inherent in our estimates of market value in determining inventory valuation are estimates related to economic trends, future demand for our products and technical obsolescence of our products. If future demand or market conditions are less favorable than our projections, additional inventory write-downs could be required and would be reflected in the cost of revenue in the period the revision is made. To date, we have not been required to revise any of our assumptions or estimates used in determining our inventory valuations.

We write down our evaluation equipment at the time of shipment to our customers, as it is not probable that the inventory value will be realizable.

Investments. We received Debentures and Warrants (collectively, the "AVCT Units") as consideration in connection with the Kandy Sale, which we accounted for in accordance with Accounting Standards Codification ("ASC") 820, Fair Value Measurement ("ASC 820"). We were subject to a lock-up provision which limited our ability to sell any shares of the AVCT common stock underlying the Debentures and the Warrants prior to June 1, 2021 (the "Lock-Up Period"), except in certain transactions. On September 8, 2021 (the "Debenture Conversion Date"), the Debentures were converted into 13,700,421 shares of AVCT common stock (the "Debenture Shares").

We calculated the fair value of the Debentures using a Lattice-based valuation approach, which utilizes a binomial tree to model the different paths the price of AVCT's common stock might take over the Debentures' life by using assumptions regarding the stock price volatility and risk-free interest rate. These results were then used to calculate the fair value of the Debentures at each measurement date. We used the Black-Scholes valuation model for estimating the fair value of the Warrants at each measurement date. The fair value of the Warrants was affected by AVCT's stock price as well as valuation assumptions, including the volatility of AVCT's stock price, expected term of the option, risk-free interest rate and expected dividends. Both the Lattice and Black-Scholes valuation models were based on available market data, giving consideration to all of the rights and obligations of each instrument and precluding the use of "blockage" discounts or premiums in determining the fair value of a large block of financial instruments. After the expiration of the Lock-Up Period and prior to the Debenture Conversion Date, the Company valued the AVCT Units at each measurement date by multiplying the closing stock price of AVCT common stock by the number of shares upon conversion of the Debentures and Warrants. Since the Debenture Conversion Date, the Company valued the Debenture Shares and Warrants by multiplying the closing stock price of AVCT common stock by the number of Debenture Shares and Warrants (collectively, the "AVCT Investment") it was holding at each

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measurement date. Adjustments to the fair values of the AVCT Units (prior to the Debenture Conversion Date) and AVCT Investment (subsequent to the Debenture Conversion Date) are included in Other (expense) income, net.

On August 29, 2022, we entered into a settlement agreement with AVCT which provided for, amongst other things, the cancellation of our investment in the Debenture Shares and the Warrants. Pursuant to the settlement agreement, we also entered into a Wind Down Agreement with AVCT, pursuant to which a Reseller Agreement between the parties, as previously amended, was terminated, and the Company was granted a non-exclusive perpetual license to use and modify certain intellectual property owned by AVCT comprising WebRTC gateway technology that is integrated with Ribbon’s SBCs and Application Servers. The perpetual license granted by AVCT is classified as Intangible assets, net in our consolidated balance sheet as of December 31, 2022.

The fair value of the AVCT Investment was reported as an Investment in our consolidated balance sheet at December 31, 2021. We had no investment in AVCT as of December 31, 2022 due to the settlement agreement entered into on August 29, 2022.

Warranty Accruals. We record warranty liabilities for estimated costs of fulfilling our obligations under standard limited hardware and software warranties at the time of sale. The liability for standard warranties is included in Accrued expenses and other and Other long-term liabilities in our consolidated balance sheet. The specific warranty terms and conditions vary depending upon the country in which we do business, but generally include material costs, technical support, labor and associated overhead over a period ranging from one to three years. We provide for the estimated costs to fulfill customer warranty obligations for certain of our products upon recognition of the related revenue. Warranty is included as a component of Cost of revenue in our consolidated statements of operations, and is determined based on actual warranty cost experience, estimates of component failure rates and our management's industry experience. Our sales contracts do not permit the right of return of the product by the customer after the product has been accepted.

Loss Contingencies and Reserves. We are subject to ongoing business risks arising in the ordinary course of business that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. We regularly evaluate current information available to determine whether such amounts should be adjusted and record changes in estimates in the period they become known. We are subject to various legal claims. We reserve for legal contingencies and legal fees when the amounts are probable and reasonably estimable.

Stock-Based Compensation. Our stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which is generally the vesting period.

We use the Black-Scholes valuation model for estimating the fair value on the date of grant of employee stock options. Determining the fair value of stock option awards at the grant date requires judgment regarding certain valuation assumptions, including the volatility of our stock price, expected term of the option, risk-free interest rate and expected dividends. Changes in such assumptions and estimates could result in different fair values and could therefore impact our earnings. Such changes, however, would not impact our cash flows. The fair value of restricted stock awards, restricted stock units and performance-based awards is based upon our stock price on the grant date.

We grant performance-based stock units, some of which include a market condition, to certain of our executives and certain other employees. We use a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity, and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values. We are required to record expense through the respective final vesting dates regardless of the number of shares that are ultimately earned. Once the grant date criteria have been met for a fiscal year performance period, we record stock-based compensation expense based on our assessment of the probability that the respective performance condition will be achieved and the level, if any, of such achievement. The Compensation Committee determines the number of shares earned, if any, after our financial results for each fiscal year performance period are finalized. Upon determination by the Compensation Committee of the number of shares that will be received upon vesting, such number of shares becomes fixed and the unamortized expense is recorded through the remainder of the service period, at which time any performance-based stock units earned will vest pending each executive's continued employment with us through that date.

The amount of stock-based compensation expense recorded in any period for unvested awards requires estimates of the amount of stock-based awards that are expected to be forfeited prior to vesting, as well as assumptions regarding the probability that performance-based stock awards without market conditions will be earned.

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Business Combinations. We allocate the purchase price of acquired companies to identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. Significant management judgments and assumptions are required in determining the fair value of assets acquired and liabilities assumed, particularly acquired intangible assets which are principally based upon estimates of the future performance and cash flows expected from the acquired business and applied discount rates. While we use our best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at a business combination date, our estimates and assumptions are inherently uncertain and subject to refinement. If different assumptions are used, it could materially impact the purchase price allocation and our financial position and results of operations. Any adjustments to assets acquired or liabilities assumed subsequent to the purchase price allocation period are included in operating results in the period in which the adjustments are determined. Intangible assets typically are comprised of in-process research and development, developed technology, customer relationships, trade names and internal use software.

Goodwill and Intangible Assets. Goodwill is not amortized, but instead is tested for impairment annually, or more frequently if indicators of potential impairment exist. Intangible assets with estimated lives and other long-lived assets are reviewed for impairment when events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by comparing the carrying amount of the asset to future net undiscounted pretax cash flows expected to be generated by the asset. If these comparisons indicate that an asset is not recoverable, we will recognize an impairment loss for the amount by which the carrying value of the asset exceeds the related estimated fair value.

Judgment is required in determining whether an event has occurred that may impair the value of goodwill, identifiable intangible assets or other long-lived assets. Factors that could indicate an impairment may exist include significant underperformance relative to plan or long-term projections, strategic changes in business strategy, significant negative industry or economic trends, a significant change in circumstances relative to a large customer, a significant decline in our stock price for a sustained period and a decline in our market capitalization to below net book value. We must make assumptions about future control premiums, market comparables, cash flows, operating plans, discount rates and other factors to determine recoverability.

Our annual testing for impairment of goodwill is completed as of October 1. As described above, effective in the fourth quarter of 2020, we determined that we had two operating segments: Cloud and Edge, and IP Optical Networks. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may be either an operating segment or a portion of an operating segment. For our annual impairment testing, we perform a fair value analysis using both an Income and Market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. We assess each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately.

Based upon the completion of our 2022 annual test for goodwill impairment, we determined that there was no impairment of goodwill for either of our reporting units. The results of our 2021 impairment test determined that the carrying value of our IP Optical Networks segment exceeded its fair value. The amount of the impairment was $116.0 million, was recorded in the fourth quarter of 2021 and is reported separately in our consolidated statement of operations for the year ended December 31, 2021. We determined that there was no impairment of our Cloud and Edge segment in 2021.

Leases. We account for our leases in accordance with Accounting Standards Codification ("ASC") 842, Leases ("ASC 842"). We have operating and finance leases for corporate offices, research and development facilities, and certain equipment. Operating leases are reported separately in our consolidated balance sheets at December 31, 2022 and 2021. Assets acquired under finance leases are included in Property and equipment, net, in our consolidated balance sheet at December 31, 2021. We had no finance leases at December 31, 2022.

We determine if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides us with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, we do not separate lease and non-lease components but rather, account for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term.

For operating leases, lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease

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term. The expense for finance leases includes both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. We expense all variable lease costs as incurred.

Accounting for Income Taxes. Our provision for income taxes is comprised of both current taxes and deferred taxes. The current income tax provision is generally calculated as the estimated taxes payable or refundable on tax returns to be filed for the year ended December 31, 2022. We provide for deferred income taxes based on temporary differences between financial and taxable income, net operating loss carryforwards, tax credit carryforwards and any required valuation allowances..

We assess the recoverability of all deferred tax assets recorded on the balance sheet and provide any necessary valuation allowances as required. In evaluating our ability to realize our deferred tax assets, we consider all available positive and negative evidence, including our past operating results, the existence of cumulative income in the most recent years, changes in our business operations, and our forecast of future taxable income. In determining future taxable income, we make assumptions, including the amount of state, federal and international pre-tax income, the reversal of temporary differences and the implementation of feasible and prudent tax planning strategies. These assumptions require significant judgment about the forecasts of future taxable income and are consistent with the plans and estimates we are using to manage our underlying businesses. Such assessment is completed on a jurisdiction-by-jurisdiction basis.

We have provided for income taxes on the undistributed earnings of our non-U.S. subsidiaries as of December 31, 2022, excluding Ireland and Israel, which are indefinitely reinvested. Accordingly, we are required to recognize deferred taxes for 2022 on the outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings.

We assess all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position's sustainability and is measured at the largest amount of benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and we determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of recognized tax benefit is still appropriate. The recognition and measurement of tax benefits require significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Results of Operations

Years Ended December 31, 2022 and 2021

Revenue. Revenue for the years ended December 31, 2022 and 2021 was as follows (in thousands, except percentages):

Segment revenue for the years ended December 31, 2022 and 2021 was as follows (in thousands):

The decrease in our product revenue in 2022 compared to 2021 was primarily the result of $32 million of lower sales of our Cloud and Edge SBC and NTR products. The decline in sales was primarily a result of lower spending from our North

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American Service Provider customers, offset by increased sales to Enterprise customers. These decreases were partially offset by $22 million of higher sales of our IP Optical Networks products. The increase in revenue from the sale of IP Optical Networks products was attributable to sales improving across almost all regions and multiple new customer wins.

In 2022, 28% of our product revenue was attributable to sales to enterprise customers, compared to 25% in 2021. These sales were made through both our direct sales team and indirect sales channel partners. In 2022, 30% of our product revenue was from indirect sales through our channel partner program, compared to 26% in 2021.

The timing of the completion of customer projects and revenue recognition criteria satisfaction may cause our product revenue to fluctuate from one period to the next.

Service revenue is primarily comprised of software and hardware maintenance and support (“maintenance revenue”) and network design, installation and other professional services (“professional services revenue”).

Service revenue for the years ended December 31, 2022 and 2021 was comprised of the following (in thousands, except percentages):

Segment service revenue for the years ended December 31, 2022 and 2021 was comprised of the following (in thousands):

Total service revenue from our Cloud and Edge segment was 5.1% lower in 2022 compared to 2021 due to declines in both maintenance and professional services fees. The decline in professional services revenue is directly related to lower product sales and the associated attached service activity. The lower maintenance revenue reflects decommissioning of older equipment and reduced support needs with several customers. Service revenue from our IP Optical Networks segment increased by 1.1% in 2022 compared to 2021, primarily due to higher maintenance fees from the growing installed base of product.

The following customer contributed 10% or more of our revenue in the years ended December 31, 2022 and 2021:

Revenue earned from customers domiciled outside the United States was 57% of total revenue in both 2022 and 2021. Due to the timing of project completions, we expect that the domestic and international components as a percentage of our revenue may fluctuate from quarter to quarter and year to year. Our total revenue for the years ended December 31, 2022 and 2021 was disaggregated geographically as follows (in thousands):

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Our deferred product revenue was $29 million at December 31, 2022 and $10 million at December 31, 2021. Our deferred service revenue was $104 million at December 31, 2022 and $120 million at December 31, 2021. Our deferred revenue balance may fluctuate as a result of the timing of revenue recognition, customer payments, maintenance contract renewals, contractual billing rights and maintenance revenue deferrals included in multiple element arrangements.

We expect that our total revenue in 2023 will increase modestly compared to our 2022 total revenue as our strategy to grow our IP Optical market share gains momentum. The primary source of revenue growth in 2022 was in our IP Routing portfolio, which we anticipate will continue in 2023 with the addition of several new products.

Cost of Revenue/Gross Margin. Our cost of revenue consists primarily of amounts paid to third-party manufacturers for purchased materials and services, royalties, amortization of acquired technology, inventory valuation adjustments, warranty costs, and manufacturing and services personnel and related costs. Our cost of revenue, gross profit and gross margin for the years ended December 31, 2022 and 2021 were as follows (in thousands, except percentages):

Our segment cost of revenue, gross profit and gross margin for the years ended December 31, 2022 and 2021 were as follows (in thousands, except percentages):

Our gross margin decreased by four percentage points in 2022 compared to 2021. This decrease was primarily the result of lower margins in our IP Optical Networks segment, and lower sales of higher margin Cloud and Edge products. Higher supply chain costs (including higher component costs, and higher freight and logistics expenses) and increased service expense were the primary contributors to the lower IP Optical Networks gross margin.

We believe that our gross margin will increase slightly in 2023 compared to 2022 primarily due to increased margins in our IP Optical Networks segment, driven by higher volume, product and customer mix, and lower supply chain costs.

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Research and Development. Research and development ("R&D") expenses consist primarily of salaries and related personnel expenses and prototype costs for the design, development, testing and enhancement of our products. Research and development expenses for the years ended December 31, 2022 and 2021 were as follows (in thousands, except percentages):