(19)

(11)

EP 0 968 591 A1

(12)

(43) Date of publication: 05.01.2000 Bulletin 2000/01 (21) Application number: 98909672.2 (22) Date of filing: 18.03.1998

(51) International Patent Classification (IPC)7: H04L 12/56, G06F 15/80, G06E 3/00 (86) International application number: PCT/GB9800/820 (87) International publication number: WO 9842/105 (24.09.1998 Gazette 1998/38)

(84) Designated Contracting States: BE CH DE FR GB LI (30) Priority: 19.03.1997 EP 97301842 (71) Applicant: BRITISH TELECOMMUNICATIONS public limited company London EC1A 7AJ (GB)	(72) Inventor: WEBB, Roderick Peter Woodbridge,Suffolk IP13 0DX (GB) (74) Representative: Semos, Robert Ernest Vickers et al BT Group Legal Services,Intellectual Property Department,8th Floor, Holborn Centre120 Holborn London EC1N 2TE London EC1N 2TE (GB)