Sonus Networks to File Partial Annual Report on Form 10-K for Year Ending December 31, 2003

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Company to Request 15-Day Extension to File 2003 Audited Financial Statements

CHELMSFORD, Mass., March 15, 2004 – Sonus Networks (Nasdaq: SONS) announced that it intends to file its 2003 Annual Report on Form 10-K for the year ended December 31, 2003 today, excluding its audited financial statements and other related financial information.  The Company also announced that it plans to file a Form 12b-25 (Notification of Late Filing) with the Securities and Exchange Commission (SEC) today requesting a 15-day extension to file the audited financial statements and other related financial information for its 2003 Annual Report on Form 10-K. 

The delay in filing the financial statements is the result of the Company’s previously announced detailed review of certain revenue timing issues and practices and of certain other financial statement accounts.  The Company has made considerable progress towards the completion of its review and intends to report its financial results for its fourth quarter and fiscal year ended December 31, 2003 upon completing the process. The Company will make every effort to amend its Form 10-K to include the financial statements and other omitted information by the 15th day following the original due date for the 10-K, or by March 30, 2004.

“Over the past two months, we have put a great deal of effort toward completing the review of our financials and establishing new practices and controls,” said Hassan Ahmed, president and CEO, Sonus Networks.  “At the same time, we have maintained strong focus and momentum in the business.  We look forward to completing this process as quickly as possible.”

About Sonus Networks

Sonus Networks, Inc. is a leading provider of packet voice infrastructure solutions for wireline and wireless service providers.  With its Open Services ArchitectureÔ (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services.  Sonus’ award-winning voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide.  Sonus, founded in 1997, is headquartered in Chelmsford, Massachusetts. 

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus that involve risks and uncertainties.  Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results as a result of various important factors, including those referred to in the “Cautionary Statements” section of Sonus’ Quarterly Report on Form 10-Q, dated November 10, 2003 and filed with the SEC, as well as unforeseen issues encountered in the completion of the Company’s independent investigation and of the year-end audit and pending securities litigation matters that could result in substantial cost and divert the attention of key personnel.  In addition, any forward-looking statements represent Sonus’ views only as of today and should not be relied upon as representing Sonus’ views as of any subsequent date.  While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so.

Sonus is a registered trademark of Sonus Networks.  Open Services Architecture, GSX9000 and Insignus are trademarks of Sonus Networks.  All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.