(19)

(11)

EP 1 194 863 A1

(12)

(43) Date of publication: 10.04.2002 Bulletin 2002/15 (21) Application number: 00942235.3 (22) Date of filing: 30.06.2000

(51) International Patent Classification (IPC)7: G06F 15/80, H04J 14/00, G02B 6/00 (86) International application number: PCT/GB0002/531 (87) International publication number: WO 0102/976 (11.01.2001 Gazette 2001/02)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE Designated Extension States: AL LT LV MK RO SI (30) Priority: 01.07.1999 EP 99305219 (71) Applicant: BRITISH TELECOMMUNICATIONS public limited company London EC1A 7AJ (GB)

(72) Inventors: Mackichan, John Cameron Felixstowe,Suffolk IP11 7NP (GB) Winter, Christopher Simon Newmarket CB8 7LG (GB) Robson, Michael Saxmundham,Suffolk IP17 1QW (GB) Heatley, David John Taylor Felixstowe,Suffolk IP11 8XT (GB) (74) Representative: Semos, Robert Ernest Vickers  BT Group Legal Services,Intellectual Property Department,8th Floor, Holborn Centre120 Holborn London EC1N 2TE London EC1N 2TE (GB)