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Developed Prototype Software for Worldwide Interop Event

CHELMSFORD, Mass., November 1, 2004 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that it collaborated with the National Communications System (NCS), an agency of the Department of Homeland Security, to test critical emergency services features for Government Emergency Telecommunications Service (GETS) at the recent Global MSF Interoperability (GMI) 2004 event.

GETS is an emergency telecommunications service provided by the NCS in the Information Analysis and Infrastructure Protection Division of the Department of Homeland Security. Developed in response to White House tasking, GETS provides National Security and Emergency Preparedness (NS/EP) users with a dependable and flexible switched voice and voice-band data communications service for use during periods of emergency or crisis. GETS uses existing features and services of the public switched telephone network (PSTN) with selected NS/EP augmentations and enhancements. The Wireless Priority Service (WPS) provides end-to-end priority cellular network access, transport, and egress for GETS callers.

In support of the NCS participation at GMI 2004, Sonus developed prototype software that demonstrates the use of the Session Initiation Protocol (SIP) Resource Priority Header (RPH) as a means of routing GETS emergency calls. SIP RPH is considered one of the key elements for critical government network applications, which require per call prioritization (precedence) for emergency calls in Homeland Security and military Command and Control applications.

"We are very pleased to be working closely with the NCS in developing GETS and WPS features and to have had the opportunity to test these important capabilities at the GMI 2004 event," said Steve Edwards, chief marketing officer, Sonus Networks. "Voice over IP has entered the mainstream, as major service providers around the world are delivering voice services on VoIP platforms. Interoperability among infrastructure and applications, and service providers, is key to accelerating that adoption even further, and GMI 2004 is taking an important role in making true interoperability a reality."

GMI 2004 interoperability testing was conducted October 4-16 at four carrier test labs: Qwest in the United States, BT in the United Kingdom, NTT in Japan and KT in Korea. The event tested NGN network elements key to supporting a fully integrated VoIP solution such as application servers, media servers, service brokers, call agents, bandwidth managers and other control and management systems against the specific protocols defined in MSF Implementation Agreements (IAs).

About the MSF

The Multiservice Switching Forum (MSF) is a global association of service providers and system suppliers committed to developing and promoting open-architecture, multiservice switching systems. Founded in 1998, the MSF is an open-membership organization comprised of the world's leading telecommunications companies. The MSF's activities include developing implementation agreements, promoting worldwide compatibility and interoperability, and encouraging input to appropriate national and international standards bodies. For more information about the MSF and its members, visit the MSF web site at http://www.msforum.org/.

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 Architecture (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 forward-looking statements regarding future events 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 "Risk Factors" section of Sonus' Annual Report on Form 10-K/A dated July 28, 2004 and filed with the SEC, and the "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated November 9, 2004 and filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. 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.