(19)

(11)

EP 0 835 574 A2

(12)

(43) Date of publication: 15.04.1998 Bulletin 1998/16 (21) Application number: 96920950.0 (22) Date of filing: 21.06.1996

(51) International Patent Classification (IPC):  H04M 3/ 00( . ) H04Q 3/ 00( . ) H04L 12/ 56( . ) H04Q 11/ 04( . ) (86) International application number: PCT/GB1996/001502 (87) International publication number: WO 1997/001913 (16.01.1997 Gazette 1997/04)

(84) Designated Contracting States: BE DE ES FR IE IT NL (30) Priority: 28.06.1995 GB 19950013138 (71) Applicant: GPT LIMITED Coventry, CV3 1HJ (GB)	(72) Inventor: ARNOLD, John, Spencer Northants NN7 3NN (GB) (74) Representative: Branfield, Henry Anthony  The General Electric Company, p.l.c. GEC Patent Department Waterhouse Lane Chelmsford, Essex CM1 2QX Chelmsford, Essex CM1 2QX (GB)