Eighth Amendment and Limited Term Waiver Agreement

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 4.31

EXTENSION OF WAIVER TERMINATION DATE

April 22, 2005

Inter-American Development Bank
Private Sector Department
1300 New York Avenue, N.W.
Washington, D.C. 20577
Attention: Loan Administration Unit

Export Development Canada
151 O'Connor Street
Ottawa, Ontario
Canada
K1A 1K3
Attention: Special Assets Unit

Ladies and Gentlemen:

        Reference is made to (a) the Eighth Amendment and Limited Term Waiver Agreement dated as of February 13, 2004 (as amended, supplemented or otherwise modified as of the date hereof, including by means of letter agreements between SRT, the Borrower and the Senior Lenders dated February 14, 2005 and March 30, 2005, the " Eighth Amendment ") between among SR Telecom Inc., a corporation duly organized and validly existing under the laws of Canada (" SRT "), Comunicación y Telefonía Rural S.A., a sociedad anónima duly organized and validly existing under the laws of Chile (the " Borrower "), Export Development Canada (formerly Export Development Corporation), a corporation established by an Act of the Parliament of Canada (" EDC "), and Inter-American Development Bank, an international organization established by the Articles of Agreement among its member countries (" IDB ", together with EDC, the " Senior Lenders "). Capitalized terms used herein and defined in the Eighth Amendment shall have the same respective meanings herein.

        Pursuant to Section 6 of the Eighth Amendment, the Eighth Amendment will expire upon the earliest date of occurrence of any of the events listed therein. Section 6(a) of the Eighth Amendment lists April 22, 2005 as one such event. In view of the fact that SRT continues to discuss with debenture holders and other creditors a possible restructuring of outstanding debentures together with possible new debt facilities, which transactions will require the consent of the Senior Lenders and the final terms of which are anticipated to materially impact the scope and terms of such consent, each of the parties hereto agree, subject to the conditions specified in the last paragraph of this letter, that:

        (1)   Section 6(a) of the Eighth Amendment is hereby amended in its entirety to read as follows:

        "(a) May 1, 2005;";

        (2)