(19)

(11)

EP 0 175 756 A1

(12)

(43) Date of publication: 02.04.1986 Bulletin 1986/14 (21) Application number: 85901743.0 (22) Date of filing: 13.03.1985

(51) International Patent Classification (IPC):  H04L 5/ 14( . ) H04L 25/ 497( . ) (86) International application number: PCT/US1985/000413 (87) International publication number: WO 1985/004540 (10.10.1985 Gazette 1985/22)

(84) Designated Contracting States: DE FR GB (30) Priority: 02.04.1984 US 19840596052 (71) Applicant: AT&T Corp. New York, NY 10013-2412 (US)	(72) Inventor: ANUFF, Alfredo Andover, MA 01810 (US) (74) Representative: Buckley, Christopher Simon Thirsk, et al  AT&T (UK) Ltd. 5 Mornington Road Woodford Green Essex IG8 0TU Woodford Green Essex IG8 0TU (GB)