Ribbon Communications Inc.

Credit Facility Waiver

On May 5, 2026, the Company entered into the First Amendment and Limited Waiver to Credit Agreement (the “First Amendment”) with Ribbon Communications Operating Company, Inc., HPS Investment Partners, LLC, as administrative agent, and the consenting lenders. The First Amendment (1) waives compliance with the maximum consolidated net leverage ratio financial covenant as of and for the period ending June 30, 2026, (2) increases the Maximum Consolidated Net Leverage Ratio (as defined in the 2024 Credit Facility) to 4.50:1.00 as of and for the period ending September 30, 2026, and sets the ratio for all subsequent quarters to 4.00:1.00, and (3) modifies the applicable interest rate margins for any quarter in which the Consolidated Net Leverage Ratio exceeds 3.75:1.00 to 7.00%.

The foregoing description of the First Amendment does not purport to be complete and is qualified in its entirety by reference to the full text of the First Amendment, a copy of which is filed as Exhibit 10.1 to this Quarterly Report on Form 10-Q and is incorporated herein by reference.

Insider Trading Arrangements

During the three months ended March 31, 2026, none of the Company’s directors or officers (as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934)adopted, terminated or modified a Rule 10b5-1 trading arrangement ornon-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of Regulation S-K of the Securities Act of 1933).