ATN International, Inc.

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ATN INTERNATIONAL, INC.

500 Cummings Center, Suite 2450

PROXY STATEMENT

FOR THE 2026 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 16, 2026

GENERAL INFORMATION ABOUT VOTING

This Proxy Statement is furnished in connection with the solicitation of proxies by the Board of Directors (the “Board”) of ATN International, Inc., a Delaware corporation, for use at the 2026 Annual Meeting of Stockholders to be held at our headquarters, located at 500 Cummings Center, Suite 2450, Beverly, MA 01915, on June 16, 2026, at 9:00 a.m. ET (the “Annual Meeting”), or any adjournments, postponements or continuations thereof. “We,” “our,” “us,” “ATN,” and the “Company” refer to ATN International, Inc.

Pursuant to certain rules of the U.S. Securities and Exchange Commission (“SEC”) that allow issuers to furnish proxy materials to stockholders over the Internet, we are posting our proxy materials on the Internet and delivering a Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access or request a copy of our Proxy Statement, our Annual Letter to Stockholders and our Annual Report on Form 10-K for the year ended December 31, 2025 (excluding exhibits) (the “2025 Annual Report”). We first mailed the Notice to stockholders on or about April 28, 2026, unless they requested printed copies of our proxy materials. If you would like to receive a paper or e-mail copy of our proxy materials, please follow the instructions for requesting such materials in the Notice. If you requested printed versions of these materials by mail, these printed materials will also include a proxy card for the Annual Meeting.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be held on June 16, 2026: This Proxy Statement, a letter to stockholders, and our 2025 Annual Report are available at https://ir.atni.com/financial-information.

Who Can Vote

Only stockholders of record at the close of business on April 20, 2026 are entitled to vote at the Annual Meeting. On the record date of April 20, 2026, 15,380,853 shares of common stock, par value $0.01 per share (“Common Stock”), were outstanding, with each share entitled to one vote. If your shares are registered with our transfer agent directly in your name, you are considered the stockholder of record with respect to those shares. If your shares are held in a brokerage account or by a bank or other holder of record, you are considered the beneficial owner of those shares. As a beneficial owner, you may direct your broker or other holder of record on how to vote your owned shares by following their instructions.

Voting

You may vote your shares held of record either by attending the meeting and voting in person or by proxy. To vote in person, you must attend the Annual Meeting. You do not need to register in advance to attend the Annual Meeting. On or about April 28, 2026, we mailed the Notice to stockholders, unless they requested printed copies of our proxy materials. The Notice contains instructions on how to access our proxy materials and how to vote. You may submit your proxy on the Internet or by telephone, or by mail prior to the Annual Meeting. If you requested printed copies of our proxy materials, these printed materials will also include a proxy card for the Annual Meeting. You can vote by completing, dating and returning the enclosed proxy card. Please review the instructions on the Notice or on the proxy card regarding your voting options. Any proxy that is voted according to the instructions included in the Notice or on the proxy card will be voted in the manner instructed by the stockholder, and if no instructions are given, the shares represented thereby will be voted by the proxy holders as follows:

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FOR the election of each of the director nominees named herein;

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FOR an advisory vote to approve the compensation of our named executive officers;

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