CHELMSFORD, Mass., June 24, 2004 – Sonus Networks (Nasdaq: SONSE), a leading provider of voice over IP (VoIP) infrastructure solutions, today announced that the Nasdaq Listing Qualifications Panel has granted an exception to Nasdaq’s periodic reporting requirements. Sonus received notification of the Panel’s decision following the close of market on June 23, 2004. The Panel has allowed the Company until June 30, 2004 to file its Form 10-K for the fiscal year ended December 31, 2003 and its Form 10-Q for the quarter ended March 31, 2004.

Sonus has requested a further exception from the Nasdaq Listing Qualifications Panel for additional time to regain compliance with the Nasdaq filing requirements beyond the June 30 date. There can be no assurance that the Panel will grant any further exception. Should the Panel deny the further exception, Nasdaq likely will notify the Company that it will be delisted. Sonus also intends to appeal the decision to the Nasdaq Listing and Hearing Review Council. This appeal will not stay delisting and Sonus cannot predict whether or not the Listing Council will modify or reverse the decision. In addition, the Listing Council may independently decide to review the Panel’s determination within 45 calendar days of issuance, in which case the Listing Council may affirm, modify, reverse, dismiss or remand the decision to the Panel.

The Company has made substantial progress towards the completion of its review of fiscal 2003, 2002 and 2001, and in connection with that review, the examination of other prior periods. Based on the current status of its ongoing review, the Company expects that it will restate its historical financial statements for fiscal years ended December 31, 2001 and 2002 and for the first three quarters of fiscal year 2003.

During the period in which Sonus has been conducting its financial review, the Company has seen strong demand for its products and services. Sonus has announced new customers, further expanded the applications of its solutions into the access and wireless markets, and enjoyed industry leadership as affirmed by respected research firms Synergy Research Group and In-Stat/MDR in their market analyses for Q1 2004. As previously reported, as of March 31, 2004, the Company had a cash, cash equivalents and marketable securities (short- and long-term) balance which exceeded $300 million.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its Open Services ArchitectureTM (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus’ 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. Additional information on Sonus is available at http://www.sonusnet.com.

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. Readers are referred to the “Cautionary Statements” section of Sonus’ Quarterly Report on Form 10-Q, dated November 10, 2003 and filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include, among others, uncertainties regarding the timing of the Company’s completion of the audit and filing of its Annual Report on Form 10-K/A for 2003 and future periodic reports, the possibility that Sonus may be delisted from Nasdaq, risks as to the litigation and SEC investigation with respect to the foregoing and related matters, unforeseen issues encountered in the completion of the audit, uncertainties regarding the extent to which prior period financial statements will be restated, the continued adverse effect of developments in the telecommunications industry, Sonus’ ability to grow its customer base, dependence on new product offerings, market acceptance of its products, competition from large incumbent vendors, rapid technological and market change and manufacturing and sourcing risks. 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, Insignus and Sonus Insight are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.