For more information, please contact:

University Developing 'Beyond 3G' Technology Showcase for Deutsche Telekom; Test Labs to Highlight Next-Generation Wireless Infrastructure and Services

WESTFORD, Mass., May 20, 2003 – Sonus Networks (Nasdaq: SONS) today announced that it is providing voice infrastructure solutions to the Technische Universitaet Berlin (TU Berlin) for deployment in the University's 'Beyond 3G' Testbed and Serviceware Framework. The project is sponsored by the German Federal Department for Education and Research (BMBF) and brings TU Berlin together with organizations including Deutsche Telekom AG, T-Mobile, T-Systems, Fraunhofer Institut FOKUS and the Technical University of Dresden to investigate the effective development, testing and deployment of mobile services.

"This is a very exciting project, and we are thrilled to be working with the Technische Universitaet Berlin and other project partners to create this showcase for Deutsche Telekom," said Hassan Ahmed, president and CEO, Sonus Networks. "This innovative network will be invaluable in demonstrating the advanced mobile solutions possible in 3G wireless networks and beyond."

The testbed will feature a variety of mobile infrastructure and services, with the goal of provisioning a heterogeneous 'Beyond-3G' network. Working with project partners including Sonus, TU Berlin will develop a mobile management infrastructure that will enable seamless connectivity across different access technologies and provider domains, and will support a variety of enhanced services.  

"This important project brings together leading providers of infrastructure and services to create the future of wireless networking," said Professor Sahin Albayrak, Technische Universitaet Berlin. "Sonus is recognized as a leader in carrier-class packet voice solutions in the wireline world and they have now moved into the mobile space. Their products are ideally suited to this application, and we are pleased to have them as a project partner."

Sonus Networks is providing its SMARRT Wireless solution, including the GSX9000 Open Services Switch, the Insignus Softswitch and Sonus Insight Management System. Sonus' wireless solutions deliver the features and protocol support necessary for rapid deployment in all wireless network environments including GSM, CDMA, TDMA and 3G. Carriers can implement the packet-based SMARRT Wireless solution in the 2G and 2.5G networks in service today, while enabling a seamless migration to 3G networks in the future.

TU Berlin will deploy Sonus' solutions to provide a wireless long distance network between Berlin and Bonn and to enable packet-based enhanced services such as unified communications. The testbed project was initiated in January 2002 and will be in place through January 2006.

About the DAI-Labor of the Technische Universitaet Berlin

The DAI-Labor is a research institute within the Electrical Engineering and Computer Science Faculty of the Technische University at Berlin. Since its inception in 1992 the DAI-Labor has acted as a bridge between research and industry. Graduate-level studies in "Agent technologies in enterprise applications" are now a regular part of the University's curriculum. Research in the DAI-Labor focuses on Service Engineering, Serviceware Frameworks and the construction of a Serviceware Infrastructure, all of which support the efficient development of services and applications. Services developed with these technologies behave intelligently, include extensive security measures, and are device-indendepent, network-independent and context-aware, giving the user optimal power and control over services. The Serviceware Frameworks advanced by the DAI-Labor afford the development of IP-based mobile services and applications. Berlin's Beyond 3G Testbed also supports the development and testing of such services and applications. The DAI-Labor employs over 60 graduate and undergraduate student employees, under the scientific direction of Prof. Dr.-Ing. habil. Sahin Albayrak.

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 the "Risk Factors" section of Sonus' Annual Report on Form 10-K, dated March 19, 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. These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many 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. 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. GSX9000, Insignus, Sonus Insight and Open Services Architecture are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.