T-Systems, a Division of the Deutsche Telekom Group, Deploys Complete Sonus Packet Voice Solution; Carrier to Leverage Network to Deliver Enhanced Voice Services to Multi-National Corporations

WESTFORD, Mass., July 11, 2002 - T-Systems International GmbH, a division of Deutsche Telekom (NYSE: DT), and Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today announced that T-Systems has chosen Sonus to build out its next-generation voice over IP (VoIP) network to provide business customers with enhanced voice services. T-Systems will leverage the Sonus-based network for services such as global voice VPN (virtual private network) and sophisticated call center routing facilities, with additional services to follow.

"We required a solution that would offer our key customers - multi-national corporations (MNCs) - the levels of voice quality and reliability that they normally expect from Deutsche Telekom," said Jan Geldmacher, Member of the Board of Management of T-Systems International GmbH, Telecommunications Services. "Moreover, we needed to be able to very rapidly deploy enhanced voice services to address the sophisticated requirements of these MNCs. The solutions Sonus provided addressed these requirements, and we're very pleased with the early success we have achieved."

Under the terms of a multi-million dollar contract, the two companies are collaborating to build a next-generation network that supports a variety of business applications. As the foundation of the network implementation, T-Systems has deployed a complement of Sonus' award-winning packet voice solutions, including the GSX9000^TM Open Services Switch, the Insignus^TM Softswitch and the Sonus Insight Management System.

"By deploying softswitch technologies, T-Systems can deliver both traditional and enhanced services more easily and rapidly than ever before," said Hassan Ahmed, president and CEO, Sonus Networks. "We are very excited to be working with T-Systems to make the expansion to a next-generation network that allows them to integrate new packet-based enhanced services into their product portfolio."

T-Systems will be rolling out enhanced services applications enabled through Sonus' Open Services Partner Alliance^SM (OSPA). These packet-based services enable T-Systems to resolve many of the issues normally associated with global corporate networks. Functionality includes the ability to deliver a unique, customer self-provisioning system for the global voice VPN service. This allows T-Systems MNC customers to seamlessly connect and manage multiple international office locations.

To support these initial applications, T-Systems will deploy the Sonus systems in eight countries in Europe and North America, and plans to rapidly expand the network footprint.

About T-Systems

With revenue of 13.8 billion euro in 2001, T-Systems - a division of the Deutsche Telekom Group - is Europe's second-largest integrated systems provider. By combining expertise in both information technology and telecommunications, it possesses the resources necessary to create true e-business and convergent solutions in the areas of application service providing (ASP), customer relationship management (CRM) and electronic marketplaces. T-Systems currently has approximately 42,000 employees in over 20 countries. The company is based in Frankfurt, Germany. Further information on the company and its service offering is available online at www.t-systems.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^TM (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.

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