PointOne Implements Acme Packet Session Border Controllers in Sonus-based Voice over IP Network

WESTFORD, Mass. and WOBURN, Mass., July 29, 2003 – Sonus Networks (Nasdaq: SONS) and Acme Packet today announced that Acme Packet has achieved Platinum standing in Sonus' Open Services Partner AllianceSM (OSPA), the highest level in the program. To become a Platinum OSPA Partner, companies must meet several criteria, including deployment in a live, revenue-generating service provider network together with one or more Sonus products. PointOne, a next-gen IP communications provider, has implemented Acme Packet's Net-Net session border controllers with Sonus' voice infrastructure solutions to enable peering between PointOne's voice over IP (VoIP) network and other carriers' IP networks.

"Working with Sonus Networks, we have created one of the industry's largest and most advanced VoIP networks, supporting a variety of wholesale voice services," said Sam Shiffman, vice president, engineering, PointOne. "By deploying Acme Packet's Net-Net with Sonus' voice infrastructure solutions, we are able to extend these services to a wider market by expanding our methods of interconnecting with customers."

PointOne has built an international VoIP network based on Sonus' Open Services ArchitectureTM (OSA) and voice infrastructure solutions including the GSX9000TM Open Services Switch, the InsignusTM Softswitch and the Sonus InsightTM Management System. With the Sonus infrastructure, PointOne provides enhanced IP voice services, using a SIP-based services architecture. Through the combination of the Sonus and Acme Packet solutions, PointOne now offers VoIP peering services, enabling service providers to peer with both private and public secure IP-based voice platforms for the secure transport of voice calls to any destination.

"With its advanced VoIP network, PointOne is positioned to quickly build new solutions into its service framework, addressing customer needs as they evolve, "said Michael O'Hara, vice president, marketing, Sonus Networks. "We are proud to be partnering with Acme Packet to further the success of PointOne and its customers, and we are pleased that Acme Packet has advanced to Platinum standing in the OSPA."

"Working together with Sonus, Acme Packet is enabling service providers such as PointOne to maximize the reach of their networks by peering with other, previously incompatible, service provider networks around the globe, "said Jim Hourihan, vice president, marketing and product management, Acme Packet. "By deploying our Net-Net session border controllers in their Sonus-based network, PointOne has architected a technologically advanced network for the secure, high-quality, end-to-end delivery of enhanced revenue generating IP services."

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 verifies product interoperability, performs trial testing and ultimately produces complete solutions. To find additional information on the OSPA, including a list of all OSPA partners, log on to http://www.sonusnet.com/partners/index.html.

About Acme Packet

Acme Packet enables network service providers to deliver premium, interactive communications - voice, video and multimedia sessions - across IP network borders. Our award-winning Net-Net family of session border controllers satisfies critical security, service assurance and law enforcement requirements in wireline, wireless and cable networks. Established in August 2000 by networking industry veterans, Acme Packet is a privately held company headquartered in Woburn, Massachusetts. For more information, contact us at +1 781.756.6800, or visit us at www.acmepacket.com.

About PointOne

Established in 1998 PointOne is the largest pure VoIP provider in the US. An enhanced service provider, the company offers a suite of next generation IP products and services including IP Centrex, origination, termination, pre-paid, 800 access, peering and others. Additionally, the network architecture is multi-layered, which provides higher quality, more robust, secure and controllable features than competitive IP voice providers that utilize the public Internet. Ranked #1 vendor in performance and reliability by the largest carriers in the U.S., PointOne is a privately held company based in Austin, Texas. For more information contact us at 512-735-1200, or visit us at www.pointone.com.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice 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, 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 "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated May 9, 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 Partner Alliance is a service mark 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.

For more information, please contact:

Sonus Networks:
Media Relations
Beth Morrissey
978-589-8579
bmorrissey@sonusnet.com

Acme Packet
Media Relations
Annalisa Ouellette
781-756-6836
aouellette@acmepacket.com

Sonus Networks:
Investor Relations
Jocelyn Philbrook
978-589-8672
jphilbrook@sonusnet.com

PointOne
Media Relations
Steve Braasch
512-735-1200
sbraasch@pointone.com