Sonus Networks Announces Support for End-to-End IPv4-to-IPv6 Connectivity Across Entire Product Line

New Software Release Allows Existing Customers to Enable IPv4-to-IPv6 Interworking with a Simple Software Upgrade

WESTFORD, Mass., June 1, 2011 – Sonus Networks, Inc. (Nasdaq: SONS), a market leader in next-generation IP-based network solutions , today announced the availability of a software upgrade that delivers on the company's plan to support IPv6 across its entire product line. As a result, Sonus customers can be assured their infrastructure will work effectively with both IPv4 and IPv6 technologies while the industry's transition to full IPv6 is underway. The decision to offer both IPv4 to IPv6 interworking in the Sonus product set, both in current products and retroactively, ensures that customers are able to migrate seamlessly, and on their own schedule, without interrupting existing services or requiring the deployment of additional hardware or network partitions.

"IPv6 is another example of how networks are becoming increasingly hybrid as multiple protocols and technologies must co-exist through lengthy transitions," said Joe McGarvey, principal analyst for IP services infrastructure at Current Analysis. "Much like the TDM-to-IP modernization of networks, which is expected to take years to complete, transitions like IPv4 to IPv6 will result in mixed-mode networks for a long time to come, and will require solutions that bridge disparate technologies and addressing schemes to help customers migrate at their desired pace. You can't just flip a switch."

Sonus initiated its IPv6 strategy with the release of its second-generation Session Border Controller (SBC), the NBS5200 TM , featuring native support for IPv4 and IPv6 devices. Since then, Sonus has added IPv6 support to its advanced network solutions including the NBS9000 Network Border Switch, GSX9000^TM Softswitch and PSX™ Centralized Routing and Policy Server . The release of the new software upgrade extends Sonus's pioneering IPv6 initiatives by providing full support for IPv4-to-IPv6 interworking across its entire product portfolio.

"Implementing IPv6 has been top of mind as our enterprise customers look to the future of IP networking," said Harold Teets, senior vice president of Information and Network Technology and CIO/CTO at tw telecom, a Sonus customer. "As IPv6 implementations take hold and continue to grow across the Internet, we have the capabilities and are ready to support our customers' needs to build out their IPv6 strategies. We will help them gain even greater business efficiencies as they seamlessly integrate our innovative technologies like optical transport, business Ethernet and international IP VPN services. Sonus Networks shares our view of this migration path."

The Sonus IPv6 strategy is built on a three-pronged approach to IPv4-to-IPv6 interoperability that provides a holistic solution for network operators:

Dual-Stack IPv4 and IPv6 support – This makes all the Sonus products "bi-lingual" with both IPv4 and IPv6 stacks and provides an application layer that can use either. This ubiquitous dual-stack capability makes Sonus's products ready to operate in any network- one that uses IPv4, or IPv6, or both IP versions at once.
Session Border Controller Interworking – As part of its long-range IPv6 planning, Sonus designed the NBS5200 session border controller to be IPv6-ready from its introduction in 2010. Both the Sonus NBS5200 and NBS9000 Network Border Switches can connect to peer networks and equipment flexibly by mediating IP-multimedia communications between IPv4-only and IPv6-only devices, including mixed environments where signaling and media are on different stacks.
Parallel and Simultaneous Deployment – The Sonus product suite is carefully designed to enable IPv6 in parallel with IPv4 on the same hardware interfaces. This avoids costly re-configurations by eliminating the need to deploy separate IPv6-only networks or to provision separate IP Trunk Groups and interfaces.

"Like most technology evolutions, including the migration from TDM to IP, the world is not a binary place and people expect that their IP services will keep on working regardless of changes in technology," said David Tipping, vice president of marketing and product management at Sonus Networks. "In the real world, organizations of all kinds will have to conduct operations in a mix of IPv4 and IPv6 for some time. Our customers can bridge from one type of network to another, one technology to the next, at their own pace and without incurring re-configuration costs."

The Sonus software release was made generally available to Sonus customers at the end of April 2011.

About Sonus Networks

Sonus Networks, Inc. is a leader in IP networking with proven expertise in delivering secure, reliable and scalable next-generation infrastructure and subscriber solutions. With customers in over 50 countries across the globe and over a decade of experience in transforming networks to IP, Sonus has enabled service providers and enterprises to capture and retain users and generate significant ROI. Sonus products include media and signaling gateways, policy/routing servers, session border controllers and subscriber feature servers. Sonus products are supported by a global services team with experience in design, deployment and maintenance of some of the world's largest and most complex IP networks. For more information, visit .

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 Item 1A "Risk Factors" of Sonus' Annual Report on Form 10-K for the year ended December 31, 2010 and all subsequent Quarterly Reports on Form 10-Q, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. 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, except as required by law.

Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.

For more information, please contact:

Sonus Networks:
Aline Kaplan
alkaplan@sonusnet.com
+1 978-614-8167

Paul Roberts
sonus@daviesmurphy.com
+1 781-418-2418