Ribbon Communications Inc.

REPORT OF INDEPENDENT RE****GISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and the Board of Directors of Ribbon Communications Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Ribbon Communications Inc. and subsidiaries (the "Company") as of December 31, 2025 and 2024, the related consolidated statements of operations, comprehensive income (loss), stockholders' equity, and cash flows, for each of the three years in the period ended December 31, 2025, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2025, based on criteria established inInternal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 26, 2026, expressed an unqualified opinion on the Company's internal control over financial reporting.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current-period audit of the financial statements that were communicated or required to be communicated to the audit committee and that (1) relate to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Revenue Recognition - Refer to Notes 2 and 16 to the Financial Statements

Critical Audit Matter Description

The Company recognizes revenue from two primary sources: products and services. Generally, contracts with customers contain multiple performance obligations, consisting of products and services. For these contracts, the Company accounts for individual performance obligations separately if they are considered distinct. When an arrangement contains more than one performance obligation, the Company will allocate the transaction price to each performance obligation on a relative standalone selling price basis. The Company utilizes the observable price of goods and services, including when they are sold separately to similar customers, in order to estimate standalone selling price.

Management is required to use judgment to develop its estimates of standalone selling price. Auditing the Company’s estimates of standalone selling price required a high degree of auditor judgment and an increased extent of effort, including the need to involve our data analytics specialists to assist in the testing of the standalone selling price analyses given the judgment required by management in this area.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to the testing of management’s estimation of standalone selling prices included the following, among others:

Goodwill - Cloud and Edge Reporting Unit - Refer to Notes 2 and 9 to the Financial Statements

Critical Audit Matter Description

The Company’s evaluation of goodwill for impairment involves the comparison of the fair value of each reporting unit to its carrying value. The Company used a combination of the income and market approaches to estimate reporting unit fair value. With respect to the income approach, management is required to make significant estimates and assumptions related to discount rates and forecasts of future revenues and profit margins. Changes in these assumptions could have a significant impact on either the fair value, the amount of any goodwill impairment charge, or both. The goodwill balance was $301 million as of December 31, 2025, of which $225 million was allocated to the Cloud and Edge Reporting Unit (“Cloud and Edge”).

Given the significant judgments made by management to estimate the fair value of Cloud and Edge, performing audit procedures to evaluate the reasonableness of management’s estimates and assumptions related to the selection of the discount rate and forecasts of future revenues and profit margins required a high degree of auditor judgment and an increased extent of effort, including the need to involve our fair value specialists.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to the discount rate and forecasts of future revenues and profit margins, used by management to estimate the fair value of Cloud and Edge, included the following, among others:

/s/Deloitte & Touche LLP

Dallas, Texas

February 26, 2026

We have served as the Company's auditor since 2005.