Sonus Joins Network of Companies To Improve Interoperability and Deliver Innovative, Cost Effective IP-based Connectivity between Carriers and Enterprises

WESTFORD, Mass., April 29, 2009 – Sonus Networks Inc. (Nasdaq: SONS), providing network transformation through IP communications technology, today announced it has joined the Avaya DevConnect program to accelerate the rapid deployment and use of SIP based IP business trunks. Avaya Inc., a leading global provider of business communications applications, systems and services, has built a community to promote the development, compliance-testing and co-marketing of innovative solutions that are compatible with standards-based Avaya solutions. Sonus IP Business Trunks replace legacy TDM voice circuits, making it easier for carriers and enterprises to connect disparate locations, overlay new services and reduce operating costs by eliminating duplicate PRI circuits for voice and data.

Sonus will test its SIP based IP business trunk interoperability with Avaya’s Communications Manager and IP Office Platforms. Testing activities will include encryption of both the audio and signaling paths so that carriers and enterprise customers can benefit from the robust security capabilities of the Sonus Network Border Switch (NBS) together with Avaya’s Communication Manager. By testing industry standard SRTP and TLS security across the connection, customers will have an additional measure of assurance that privacy can be maintained across an IP based voice connection.

"Service providers need to react quickly to the evolving needs of their enterprise customers, while maintaining operating margins in a pressured economy. Sonus is working with market leaders like Avaya to pre-test that our respective business solutions can be rapidly deployed together to meet customer needs,” said Shailin Sehgal, vice president, marketing and product management at Sonus Networks. “These collaborations can help to reduce a carrier’s overall cost and time to service. For any carrier or operator looking to upgrade their network, reducing the time to revenue is critical."

The Avaya DevConnect program promotes the development, compliance-testing and co-marketing of innovative solutions that are compatible with standards-based Avaya solutions. Member organizations have expertise in a broad range of technologies – including IP telephony, contact centers and mobility applications – helping companies extend the value of multi-vendor networks and transform voice into an intelligent business application that delivers true value to the bottom line.

"Development partners like Sonus Networks are helping Avaya dramatically expand the connectivity options available to its customers," said Eric Rossman, vice president, developer relations and technical alliances, Avaya. "By leveraging IP business trunks, we’re able to provide the tools businesses need to change the way they work and to establish a true competitive advantage in the marketplace. They are better able to use unified communications applications to make critical information readily available to both employees and customers, regardless of where they are or how they choose to communicate."

Membership information and a listing of solutions developed and tested under the DevConnect program are available at www.avaya.com/devconnect.

About Avaya

Avaya is a global leader in enterprise communications systems. The company provides unified communications, contact centers, and related services directly and through its channel partners to leading businesses and organizations around the world. Enterprises of all sizes depend on Avaya for state-of-the-art communications that improve efficiency, collaboration, customer service and competitiveness. For more information please visit www.avaya.com. For more information on the Avaya DevConnect program, visit www.avaya.com/devconnect.

About Sonus Networks

Sonus Networks Inc., providing network transformation through IP communications technology, is leading the evolution of communications networks to support the multi-media, multi-device demands of today’s digital lifestyle. Sonus solutions and services enable fixed, mobile and cable operators to gain network awareness and new multi-media capabilities essential to retaining and expanding their subscriber base. Through standards based interoperable solutions and services, Sonus extends the investments made in traditional networks by enabling operators to seamlessly migrate to next generation technology and deliver the secure, reliable, scalable and cost-effective network needed to grow their business. For more information visit 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. For a discussion of the risks and uncertainties which could cause actual results to differ from those contained in the forward-looking statements, see “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2008. Risk factors include among others: the unpredictability of our quarterly financial results; risks and uncertainties associated with the Company's previous restatement of its historical stock option granting practices and accounting including regulatory actions; actions that may be taken by significant shareholders; risks associated with our international expansion; and the impact the current global financial market conditions may have on the telecommunications industry. 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.

Sonus Media Inquiries:
Lucy Millington
978-614-8240
lmillington@sonusnet.com

Avaya Media Inquiries:
Lynn Newman, Avaya
908-953-8692
lynnnewman@avaya.com