T-Systems, a Division of the Deutsche Telekom Group, Selects Sonus to Integrate and Deploy one of the World's Largest Business VoIP Services

CHELMSFORD, Mass., and Frankfurt am Main, Germany, November 2, 2005 – T-Systems, the business customer division of the Deutsche Telekom Group (NYSE: DT) and one of Europe's leading providers of information and communications technology (ICT), and Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that T-Systems has awarded Sonus Networks a multi-million dollar contract for the worldwide expansion of its business VoIP network. The agreement marks the development of one of the world's largest and most sophisticated business VoIP services networks designed for large to medium enterprise customers globally. The Sonus solution is also enabling T-Systems to deliver a new global peering service.

“We launched our business VoIP service targeting multi-national corporations with Sonus three years ago, and due to the good performance of the network we have been able to grow our business with enterprise customers,” said Bjoern Claassen, Member of the T-Systems Executive Committee. “This new network expansion gives T-Systems the flexibility to extend our service around the globe and continue to expand our portfolio of next-generation services.”

T-Systems plans initially to expand the network throughout Europe and North America, with other regions to follow. With its extended reach, T-Systems will deliver enhanced services such as their global voice virtual private network service (VPN); iST, International Service Telephony; VIP, Voice Interactive Portal and VNS, IP Voicenet Services. With the new global peering service, T-Systems will allow service providers to securely connect via IP to the T-Systems IP-based network.

"Sonus is committed to helping our customers stay at the forefront of new technology and services," said Hassan Ahmed, chairman and CEO, Sonus Networks. "By initiating a significant expansion of their Sonus-based VoIP network, T-Systems will be able to deliver unified next-generation services to enterprise customers around the globe that meet the requirements for scalability and reliability that business customers demand. We are pleased to be working with T-Systems to support their strategic vision for business services."

The contract includes Sonus' latest technology introduction, the GSX4000 Open Services Switch, which will enable T-Systems to cost-effectively expand their VoIP network to less densely populated regions around the world. T-Systems has also selected Sonus to supply and deploy a fully integrated VoIP solution, including applications from partners in its Open Services Partner Alliance (OSPA). OSPA is the industry's largest interoperability program and is deployed in customer networks around the globe. Sonus' OSPA includes over 150 leading independent vendors that enable the seamless deployment of feature rich services. As a foundation for the network, T-Systems is utilizing key components in the Sonus architecture, including the GSX9000™ Open Services Switch, the NBS Network Border Switch, the PSX™ Call Routing Server and the Sonus Insight™ Management System.

About T-Systems

T-Systems is one of Europe's leading providers of information and communications technology (ICT). Within the Deutsche Telekom Group, T-Systems is responsible for supporting the business customer segment, ranging from medium-sized and large companies all the way up to multinational corporations and public institutions. The company has 51,000 employees in over 20 countries worldwide and posted revenues of nearly €13 billion in 2004. The company optimizes processes and cuts costs for its customers, thus providing them additional flexibility for their core business. It does this by making targeted use of industry expertise and cutting-edge technology. T-Systems' services encompass all levels of the information and communications technology value chain, spanning from ICT infrastructure and ICT solutions, up to, and including, business process management. For more information about the company and its services, see www.t-systems.com.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. 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, dated March 15, 2005, and the "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated August 8, 2005, both filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the company. 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, Inc. Sonus GSX9000 Open Services Switch, PSX Call Routing Server, SGX Signaling Gateway, and the Sonus Insight Management System are trademarks of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.