NORTH BILLERICA, Mass. -- Avici Systems Inc. (NASDAQ: AVCI), today announced that William J. Leighton has accepted the permanent position of President and Chief Executive Officer. Mr. Leighton was appointed interim CEO on November 15, 2004.

Mr. Leighton joined Avici's Board in May of 2004 upon retirement from AT&T where he spent 27 years at AT&T Labs and Bell Labs. Most recently, Mr. Leighton served as Vice President of Research, and previously as Vice President of Network Development, where he led the design and development of AT&T's IP and data networks and services.

Avici Systems Inc.