Sonus Brings The Power Of Voice Over Broadband To Mexico

CHELMSFORD, Mass. - February 22, 2005 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, and Marcatel International, a leading provider of integrated communications services in Mexico, today announced that Marcatel has chosen Sonus' industry-leading Open Services Architecture (OSA) to deliver VoIP functionality over Marcatel's fiber optic network. To meet the growing demand for multi-media capabilities delivered through high-speed Internet connections, Marcatel plans to roll out VoIP offerings to businesses and cable operators in Mexico.

"Our agreement with Sonus is integral to our business strategy of delivering a comprehensive suite of voice and data services throughout Mexico," said Tim Heaney, Operations Director, Marcatel. "Leveraging Sonus' proven solutions, we are cost-effectively expanding our voice offerings into the enterprise and consumer markets by providing a full range of next-generation telephony services."

The first phase of the deployment will begin at one of Marcatel's main branches located in Monterrey where Marcatel is deploying the full Sonus solution, including the GSX9000™ Open Services Switch and the Insignus™ Softswitch. In this phase of the deployment, Marcatel will deliver access services to businesses and consumers by directly linking them to Marcatel's Sonus-based network. The Sonus platform will offer users a variety of standard local services that they have traditionally enjoyed through a circuit-based solution, but by delivering through an enhanced IP environment, they will have added flexibility to easily incorporate new features in the future. Based on the successful implementation in this region, Marcatel will deploy Sonus' packet voice infrastructure solutions in other markets as well.

"Recognizing the rapid growth in high-speed Internet connections, Marcatel is making the transition to delivering broadband access services," said Steve Edwards, chief marketing officer, Sonus Networks. "We are extremely pleased that Marcatel has selected Sonus as its partner to enter this new segment of the market. Sonus' voice over broadband solutions have been proven in major networks around the globe, and we are excited to bring these capabilities to Marcatel."

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its Open Services ArchitectureTM (OSA), 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.

About Marcatel

Marcatel is one of the largest carriers in Mexico, providing service to over 35,000 business customers through its 19 customer care centers located throughout the country. The company offers carrier infrastructure, IP and data services. Marcatel provides integrated communication services including long distance, 800 numbers, prepaid calling cards, calling cards with international coverage as well as telephony administration and cost control systems. Marcatel's IP broadband data services include Internet access using DSL, dedicated and wireless access, dial-up and private line. The company also provides carrier services such as dark fiber, private lines, co-location and spectrum frequencies for microwave access. Additional information on Marcatel is available at http://www.marcatel.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/A dated July 28, 2004 and filed with the SEC, and the "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated November 9, 2004 and filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. In addition, 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. Open Services Architecture, GSX9000, Insignus and Sonus Insight are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.