AVICI SYSTEMS SCHEDULES Q4'06 AND YEAR END EARNINGS RELEASE DATE AND TIME

N. Billerica, MA, January 31, 2007 — Avici Systems (Nasdaq: AVCI), today announced it will release financial results of its fiscal fourth quarter ended December 31, 2006, on February 14, 2007 after the close of the market and will host a conference call on February 15 at 8:30 a.m. EST, to be broadcast live over the Internet.

To participate via telephone, the dial-in number is 800-288-8976. Please call ten minutes prior to the scheduled conference call time. For live Webcasting, go to the Avici Web site at www.avici.com and access the investor relations section, clicking on either the live Webcast link or the microphone icon to listen.

The conference call will be archived on the Avici Web site. A replay will be accessible by telephone after 1:00 p.m., for approximately 48 hours afterward. To replay the call dial 800-475-6701 using the access code 862023.

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.