Three New Members Join Sonus Networks' Open Services Partner Alliance

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2Wire, Sage Instruments and Tainet Expand Program Offerings with Next-Generation Products

WESTFORD, Mass., February 20, 2002 – Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today announced three new members to its Open Services Partner AllianceSM (OSPA), further strengthening the program's diverse spectrum of packet-based technologies and solutions. Sonus welcomed 2Wire, Inc., Sage Instruments, Inc., and Tainet Communication System Corp. to the OSPA, which brings together best-of-breed technologies and applications. By joining the program, these vendors have demonstrated the importance of establishing standards-based interoperability between next-generation communications products to deliver complete carrier-class voice, data and multimedia solutions.

"Sonus has always had a focus on delivering cutting-edge communications technology that adds significant value for our customers," said Terri Griffin, vice president of marketing, Sonus Networks. "By championing standards-based interoperability with our partners, we can extend the reach of that goal and ensure that our customers have access to the most comprehensive packet voice solutions."

Companies joining the Sonus OSPA today offer the following solutions:

• 2Wire develops integrated products that deliver broadband service and content throughout the home. 2Wire's complement of broadband solutions, including its line of HomePortal' residential gateways, enable feature-rich Internet, telephony, entertainment and other services that can be delivered to computers, phones and entertainment equipment. (www.2Wire.com)
• Sage Instruments has developed innovative, cost-effective testing solutions for the telecommunications industry. Sage's test systems evaluate voice quality - clarity, echo and delay - on next-generation voice-over-packet networks, as well as transmission, signaling and provisioning in TDM (time division multiplexing) or analog environments. (www.sageinst.com)
• Tainet Communications delivers a suite of fax and voice over internet protocol (F/VoIP) products that allow service providers to quickly integrate and provide voice over IP services to end users. With Tainet's Venus series of F/VoIP gateways, the business user's existing analog phones, PBXs, key systems, faxes and data LANs can be connected to a service provider's managed IP network via various broadband access technologies. (www.tainet.net)

About Sonus' OSPA

Sonus Networks' Open Services Partner Alliance Program provides a framework that offers service providers end-to-end packet-based network solutions using best-of-breed technologies and applications. The goal of the OSPA is to empower standards-based interoperability between applications, hardware vendors, and the Sonus product family. An integral part of the Sonus OSPA, the OSPA Interoperability Laboratory is the first in the industry where product interoperability is verified, trial testing is performed and complete solutions are ultimately produced. To find additional information on the OSPA, including a list of all OSPA partners, log on to http://ospa.sonusnet.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 Sonus' Quarterly Report on Form 10-Q, dated November 14, 2001, 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 Company's ability to grow its customer base, dependence on new product offerings, market acceptance of its products, integration risks relative to its acquisition of telecom technologies, rapid technological and market change and manufacturing and sourcing risks.

Open Services Partner Alliance is a service mark of Sonus Networks and Open Services Architecture is a trademark of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.