(19)

(11)

EP 0 521 027 A1

(12)

(43) Date of publication: 07.01.1993 Bulletin 1993/01 (21) Application number: 91905851.0 (22) Date of filing: 22.03.1991

(51) International Patent Classification (IPC):  H04L 12/ 18( . ) (86) International application number: PCT/AU1991/000111 (87) International publication number: WO 1991/015070 (03.10.1991 Gazette 1991/23)

(84) Designated Contracting States: DE FR GB IT (30) Priority: 22.03.1990 AU 19900009227 (71) Applicant: AUSTRALIAN AND OVERSEAS TELECOMMUNICATIONS CORPORATION LTD. Melbourne, VIC 3000 (AU)	(72) Inventor: LITTLEWOOD, Morgan Elwood, VIC 3184 (AU) (74) Representative: Charlton, Peter John (GB)  Elkington and Fife Prospect House 8 Pembroke Road GB-Sevenoaks, Kent TN13 1XR GB-Sevenoaks, Kent TN13 1XR (GB)