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Four New OSPA Members Deliver Range of Products and Services, Expand International Scope of Alliance

WESTFORD, Mass., August 12, 2002 - Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today announced that InnoMedia, Inc., Personeta, Inc., Psytechnics, Ltd. and SkyWave, Inc. are the latest telecommunications companies to join Sonus' Open Services Partner Alliance (OSPA).

The OSPA brings together leading telecom hardware and software vendors providing a range of products such as enhanced services, network infrastructure and operations support systems (OSS). The companies entering the program today deliver solutions ranging from enhanced services such as conferencing, prepaid calling and auto attendant, to cable access devices such as MTAs (multimedia terminal adapters) and EMTAs (embedded multimedia terminal adapters), to QoS management solutions.

"We are very pleased to welcome these partners into our program as they expand the breadth of our solution offerings for enhanced services and cable solutions," said Michael O'Hara, vice president, marketing, Sonus Networks. "The OSPA continues to be an excellent breeding ground for some of the newest upcoming IP-based services and infrastructure companies."

Partners joining the OSPA today include:

• InnoMedia delivers a family of highly interoperable, feature-rich broadband VoIP CPE devices or IADs targeted at broadband service providers. InnoMedia's offerings include the standalone MTA 3328 with 1, 2 or 4 voice ports, the EMTA 3528 with 1 or 2 voice ports and the MTA 3308 IP Phone.
• Personeta offers the TappS Telco Application Server, an open application platform for the creation and delivery of enhanced, value-added telecom services on carrier networks. Complementing this application server, Personeta delivers several turnkey applications such as prepaid calling and auto attendant.
• Psytechnics provides a portfolio of products for quality assessment of communications networks and specific technologies such as mobile and VoIP. Psytechnics' PsyVoIP measures live VoIP customer calls to determine the speech quality delivered by a VoIP network for each and every call.
• SkyWave offers enhanced voice and billing solutions to the wireless and VoIP markets in Japan. SkyWave develops a SIP-based softphone product, "SkyPhone," for Windows and Windows CE platforms, a SIP-based conferencing application, "SkyConference," and a real-time billing solution, "SkyPath."

About Sonus' OSPA

Sonus Networks' Open Services Partner Alliance program provides a framework that offers service providers end-to-end packet-based network solutions using best-of-breed technologies and applications. The goal of the OSPA is to empower standards-based interoperability between applications, hardware vendors, and the Sonus product family. An integral part of the Sonus OSPA, the OSPA Interoperability Laboratory is the first in the industry where product interoperability is verified, trial testing is performed and complete solutions are ultimately produced. To find additional information on the OSPA, including a list of all OSPA partners, log on to http://ospa.sonusnet.com.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture (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 Westford, 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 Sonus' Quarterly Report on Form 10-Q, dated May 10, 2002 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. These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many emerging service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change and manufacturing and sourcing risks.

Open Services Partner Alliance is a service mark of Sonus Networks and Open Services Architecture is a trademark of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.