Sonus Networks Receives Miercom "Performance Verified" Award for Its Session Border Controllers at 2011 Enterprise Connect Show

WESTFORD, Mass., March 7, 2011 – Sonus Networks Inc., (Nasdaq: SONS), a market leader in next-generation IP-based network solutions, today announced that it received the Miercom "Performance Verified" Award in a brief ceremony at last week's Enterprise Connect trade show in Orlando, Florida.

Specialists in networking and communications-related product testing, Miercom awarded the Sonus NBS5200TM and NBS9000TMNetwork Border Switches "Performance Verified" status based on independent lab testing. Hands-on testing proved that the Sonus NBS5200 has a robust architecture, scales successfully to 256,000 end points, and delivers high availability and rapid recovery from network outages. The Miercom certification, which was announced in 2010, was the result of extensive testing. The tests concluded that Sonus's Network Border Switch (NBS) portfolio delivers extraordinary performance even under the most adverse of conditions where other products often exhibit significant performance breakdown. The full reports on both products can be read at www.miercom.com/sonus.

"Sonus has earned the "Performance Verified" Award for the NBS5200 and NBS9000 Network Border Switches. We were impressed with the scalability and capacity of the NBS5200, and verified that it exceeded the capacity of other market-leading products," said Rob Smithers, CEO of Miercom. "With regard to the total number of endpoints successfully registered, maximum number of simultaneous calls processed and performance under overload conditions, the NBS5200 proved it has the processing horsepower to meet both present and future carrier-class demands."

Miercom tested the NBS5200 and NBS9000 under a variety of strenuous conditions including Denial of Service (DoS) attacks and the high-volume spikes that can follow after a widespread power outage. Additionally, the results of the independent third-party tests validated the Sonus claim that the NBS5200 is the session border controller with the greatest session density and throughput. The NBS5200 and NBS9000 network border switches can withstand severe denial of service attacks while allowing legitimate traffic to pass through and continuing to process calls successfully.

"Third-party validation of vendor claims is essential when users are selecting technology. Receiving this award from Miercom is yet another validation of the NBS5200, which has been very well-received by the entire industry," said Bob Bradley, product line manager for security solutions at Sonus Networks. "The momentum for the NBS5200 and NBS9000 is undeniable; we are seeing traction within service providers and enterprises alike."

The full test results and reports can be also found on the Sonus site:

NBS9000: /content/whitepaper-details/Miercom-Lab-TestingPerformance-Report-on-Sonus-NBS9000/17.

NBS5200: /content/whitepaper-details/Miercom-Lab-TestingPerformance-Report-on-Sonus-NBS5200/23.

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 www.sonusnet.com.

About Miercom, Inc.

Miercom has hundreds of product-comparison analyses published over the years in leading network trade periodicals including Network World, Business Communications Review, Tech Web - No Jitter, Communications News, xchange, Internet Telephony and other leading publications. Miercom's reputation as the leading, independent product test center is unquestioned. Miercom's private test services include competitive product analyses, as well as individual product evaluations. Miercom features comprehensive certification and test programs including: Certified Interoperable, Certified Reliable, Certified Secure and Certified Green. Products may also be evaluated under the NetWORKS As Advertised program, the industry's most thorough and trusted assessment for product usability and performance. Additional information on Miercom can be found at www.miercom.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 Item 1A "Risk Factors" of Sonus' Annual Report on Form 10-K for the year ended December 31, 2009 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:

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

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

Miercom
Maria Inguaggiato,
+1-609-490-0200 *820
Marketing Communications Assistant
minguaggiato@miercom.com