Epana Networks Delivers International Prepaid Calling Services on Sonus Networks VoIP Infrastructure

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SIP Solutions Enable New York-based Carrier to Provide Highly Competitive Prepaid Offering

WESTFORD, Mass., May 13, 2003 – Sonus Networks (Nasdaq: SONS) and Epana Networks today announced that Epana has deployed Sonus' packet voice infrastructure solutions to support the delivery of international and domestic prepaid calling services. Epana's voice over IP (VoIP) network is commercially operational and has been carrying voice traffic since September 2002.

"We are focused on providing next-generation telecommunications solutions that deliver greater value to our customers, "said Elie Seidman, founder and CEO, Epana Networks. "The packet voice network that we have implemented with Sonus is helping us to achieve that goal and enabling us to offer highly flexible prepaid calling services at extremely cost-effective rates."

At the foundation of Epana's VoIP network are Sonus' Open Services Architecture(TM) (OSA) and voice infrastructure solutions, including the GSX9000(TM) Open Services Switch, the Insignus(TM) Softswitch and the Sonus Insight(TM) Network Management System. Additionally, Epana has implemented a complete SIP-based prepaid calling card solution from Sonus' Open Services Partner AllianceSM (OSPA) members Pactolus Communications Software Corporation and Convedia Corporation. Epana has deployed Pactolus' SIPware(TM) Prepaid Calling Card application and RapidFLEX(TM) Application Server in conjunction with Convedia's CMS-6000 and CMS-1000 Media Servers. With the Sonus VoIP infrastructure and enhanced services applications in place, Epana calling card users can place domestic long distance calls, as well as international calls to Asia, Africa, the Middle East and Latin America, at extremely competitive rates. 

"Epana's network implementation underscores the power of voice over IP in providing a flexible, reliable and cost-effective alternative for deploying enhanced services applications such as prepaid calling," said Michael O'Hara, vice president, marketing, Sonus Networks. "We are pleased that Epana chose Sonus as its partner in building out its next-generation voice network, and we look forward to building on the success that we have already achieved together."

About Epana Networks

Epana Networks is a facilities-based telecommunications service provider delivering a range of industry-leading prepaid calling card services. Epana provides prepaid services for wholesale and retail customers to over 200 countries worldwide. Leveraging its private fiber network, Epana delivers high quality, low cost telecommunications services to customers across the country and around the world. For more information, visit www.epana.com or e-mail info@epana.com.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning 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 Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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, dated March 19, 2003 and filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change and manufacturing and sourcing risks. 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. Open Services Partner Alliance is a service mark of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.