Avici Showcases Real-Time IP Network at Supercomm 2004; Demonstrates Fast Convergence with RAPID, Integrated VoIP and Multi-Service Solutions.

CHICAGO -- Avici Systems, Inc., (Nasdaq: AVCI) showcases its continued commitment to service providers by delivering a proven converged Real-Time IP/MPLS core network. Visitors to Supercomm 2004 can witness Avici breakthroughs in carrier-class routing and integrated solutions demonstrated at multiple locations throughout the show.

At the Avici booth (Booth #25210), Avici will graphically demonstrate the impact of its revolutionary RAPID(TM) fast convergence capability on carrier networks. Also showcased will be end-to-end VoIP solutions and Multi-Service Convergence solutions developed together with Nortel Networks.

--Reliable Alternate Paths for IP Destinations (RAPID) Avici's RAPID technology for self-healing link and node protection will be shown for the first time at Supercomm 2004. Visitors will have the opportunity to see in graphic detail how RAPID provides self-healing network-wide protection with sub 50ms convergence.

--Integrated VoIP Solutions -Together with Nortel Networks, Avici Systems is featuring the integration of its high-availability core routers with Nortel's Succession Softswitch Portfolio for end-to-end toll-quality VoIP services. Delay and jitter sensitive voice calls that originate and terminate within wireline, wireless, or cable access networks are supported by an end-to-end solution for carrier-class reliability, performance and management.

--Multi-Service Convergence Solutions - Avici Systems will feature end-to-end multiservice solution offerings in conjunction with Nortel Networks platforms, including its newly launched Multiservice Provider Edge (MPE) 9000 platform. These solutions give carriers the assurance of end-to-end visibility and control by integrating all solution elements through Nortel Networks' Multiservice Data Manager for element management, fault management, service management, and performance monitoring.

Avici technology and solutions are also being showcased in live demonstrations at other industry and partner locations at Supercomm 2004 including:

--Isocore IP-Optical Pavilion (Booth #11142) - Avici, with leading vendors and service providers, will cooperate in a technology showcase coordinated by the Isocore Internetworking Lab. The IP- Optical Pavilion will demonstrate a range of cutting edge technologies for network protection, advanced service support, and cost reduction including Avici's NSR non-stop routing.

--OIF World Interoperability Demo (Booth #20334) - Avici will continue its leadership in development of IP-Optical integration standards by participating with leading optical vendors in the industry's first international multi-carrier IP-Optical interoperability demonstration. This event, conducted simultaneously across the networks of AT&T, China Telecom, Deutsche Telecom, KDDI, NTT, and Verizon, will employ Optical Internetworking Forum (OIF) signaling between vendor equipment and carrier networks.

--Nortel Networks (Booth #11326) - Avici SSR and QSR routing platforms are integral components in a live demonstration of Nortel Networks industry-leading VoIP and Multi-Service Solutions. This demo will illustrate Non-Stop Routing (a premier carrier-grade reliability feature) by demonstrating a live hitless failover. Additionally, VoIP traffic using Nortel Networks Multimedia Communication Server clients will be delivered across the Avici core.

"Avici Systems is making the converged Real-Time network a reality for carriers, as evidenced by the technologies and integrated solutions we are showcasing here at Supercomm 2004, says Steve Kaufmann, CEO of Avici Systems, "Inferior IP network reliability and the lack of integrated end-to-end solutions have prevented many carriers from successfully converging to an IP/MPLS network. Avici has developed these technologies and integrated solutions through direct carrier input to overcome obstacles to achieving the converged Real-Time IP Network."

About Avici Systems

Avici Systems Inc., headquartered in North Billerica, Mass., is a leading provider of purpose-built carrier-class routing solutions for the Internet. Avici's family of routers is designed to meet carrier requirements for the highest scalability, reliability and network availability, while lowering the total cost of building and operating their networks. The company's routing systems provide new IP solutions to some of the world's leading service providers. For more information, please visit us at www.avici.com. Avici, TSR, SSR, QSR, IPriori, Velociti, NSR, MSC, ASAP, and RAPID are trademarks of Avici Systems Inc. This release contains information about Avici's future expectations, plans, and prospects that constitute forward-looking statements for purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995. Such forward-looking statements are subject to risks and uncertainties, which could cause actual results to differ materially from those anticipated. When used in this press release, the word "will", "expected" and other similar expressions are intended to identify such forward looking statements. Such risks and uncertainties include, but are not limited to, market acceptance of Avici products, services and enhancements, customer purchasing patterns and commitments, development of the market place, product development and enhancement, intensity of competition of other vendors, technological changes and other risks set forth in Avici's filings with the Securities and Exchange Commission.

Nortel Networks, the Nortel Networks logo, the Globemark, Business Without Boundaries, MPE, Preside MDM, Passport, Shasta and Succession are trademarks of Nortel Networks.