Vice President of Engineering and Chief Architect Joins the Leadership Team to Further Develop the Company’s Innovative IP Networking Technology

WESTFORD, Mass., October 1, 2009 – Sonus Networks, Inc. (Nasdaq: SONS), providing network transformation through IP communications technology, today announced the appointment of Kumar Vishwanathan as vice president of engineering and chief architect, to further advance the company’s leading research and development initiatives. Today’s announcement is the latest in an ongoing series of significant investments by Sonus, designed to accelerate innovation and enhance the Company’s ability to deliver breakthrough technology and solutions.

The appointment of Kumar Vishwanathan to vice president of engineering and chief architect underscores Sonus’ commitment to provide carriers with the most robust, reliable, efficient and service-generating voice over IP network solutions. Based at the Company’s Westford, Mass. headquarters, Mr. Vishwanathan will be responsible for steering Sonus’ technology evolution and developing new products with a particular focus on IP-peering and session border control. Mr. Vishwanathan is an experienced leader and innovator in the area of data networking, wireless and multimedia technology, holding 15 patents to date and with more than ten applications pending in telephony, multimedia and collaboration.

“Sonus continues to make strategic business decisions that directly align with the company’s core focus of delivering industry-leading IP communications technology and we are pleased to welcome Kumar to our research and development team,” said Guru Pai, senior vice president and general manager at Sonus. “With Kumar’s considerable experience, Sonus will be even better positioned to successfully leverage the industry’s most advanced voice over IP technology.”

Mr. Vishwanathan most recently served as the co-founder and vice president of solutions for envIO Networks, a mobile content and social marketing platform provider. In this role, he led the company’s product management, system engineering and deployment teams across the US, South East Asia and India. Mr. Vishwanathan was part of the founding team at Winphoria Networks, helping the company to pioneer technology in the Wireless SoftSwitch and Push-To-Talk over cellular markets. After Motorola’s acquisition of Winphoria Networks in May 2003, Mr. Vishwanathan served as the senior director of engineering where he was responsible for overseeing the development of the company’s Core Networks product line including SoftSwitch, Media Gateway, IMS and Push-to-Talk solutions. Prior to Winphoria Networks, Mr. Vishwanathan worked at Lucent Bell laboratories defining the early softswitch architectures and the development of the Lucent SoftSwitch.

About Sonus Networks

Sonus Networks, Inc., providing network transformation through IP communications technology, is leading the evolution of communications networks to support the multi-device demands of today’s digital lifestyle. Sonus solutions and services enable fixed, mobile and cable operators to gain session awareness and deliver multi-media capabilities essential to adding value and expanding their customer and 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 and Quarterly Report on Form 10-Q for the quarter ended June 30, 2009.

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 Media Relations
Lucy Millington
978-614-8240
lmillington@sonusnet.com

RacePoint Group for Sonus
Shannon Breen/Katie Traut
781-487-4600
sonus@racepointgroup.com