UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 3, 2026

RIBBON COMMUNICATIONS INC.

(Exact Name of Registrant as Specified in its Charter)

6500 Chase Oaks Blvd., Suite 100, Plano, TX 75023

(Address of Principal Executive Offices) (Zip Code)

(978) 614-8100

(Registrant’s telephone number, including area code)

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Ribbon Communications Inc. (the “Company”) held its annual meeting of stockholders on June 3, 2026 (the “Annual Meeting”). At the Annual Meeting, the Company’s stockholders considered and voted upon the matters listed below. A total of 163,724,665 shares of common stock were present in person or represented by proxy at the Annual Meeting, representing approximately 93% of the Company’s outstanding common stock as of the April 6, 2026 record date. The following are the voting results for the proposals considered and voted upon at the Annual Meeting, each of which were described in the Proxy Statement.

Item 1 – Election of nine directors for a term of office expiring on the date of the annual meeting of stockholders in 2027 and until their respective successors have been duly elected and qualified.

All of the nominees named above were elected, having received more votes cast “for” their election than “against” their election.

Item 2 – Ratification of the appointment of Deloitte & Touche LLP to serve as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2026.

Based on the foregoing vote, Item 2 was approved.

Item 3 – The non-binding advisory vote on the compensation of the Company’s named executive officers, as disclosed in the “Compensation Discussion and Analysis” section and the accompanying compensation tables and related narratives contained in the proxy statement for the Annual Meeting.

Based on the foregoing vote, Item 3 was approved.

The Compensation Committee and the Board of Directors of the Company will consider the outcome of the advisory vote when making future compensation decisions relating to the compensation paid to the Company’s named executive officers.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.