(19)

(11)

EP 0 835 573 A1

(12)

(43) Date of publication: 15.04.1998 Bulletin 1998/16 (21) Application number: 96920985.0 (22) Date of filing: 27.06.1996

(51) International Patent Classification (IPC):  H04L 12/ 28( . ) H04N 7/ 10( . ) (86) International application number: PCT/GB1996/001538 (87) International publication number: WO 1997/001906 (16.01.1997 Gazette 1997/04)

(84) Designated Contracting States: DE FR GB (30) Priority: 28.06.1995 GB 19950013147 (71) Applicant: NORTHERN TELECOM LIMITED Montreal, Quebec H2Y 3Y4 (CA)	(72) Inventors: MILES, Andrew, Llewllyn Saffron Walden Essex CB11 3PT (GB) BELCOURT, Adrien, Joseph, Paul Maidenhead Berks SL6 3ER (GB) (74) Representative: Ryan, John Peter William, et al  Nortel Patents, London Road Harlow, Essex CM17 9NA Harlow, Essex CM17 9NA (GB)