(19)

(11)

EP 0 138 975 A1

(12)

(43) Date of publication: 02.05.1985 Bulletin 1985/18 (21) Application number: 84901557.0 (22) Date of filing: 02.04.1984

(51) International Patent Classification (IPC):  H04J 1/ 00( . ) H04M 11/ 06( . ) H04J 1/ 20( . ) (86) International application number: PCT/US1984/000483 (87) International publication number: WO 1984/004216 (25.10.1984 Gazette 1984/25)

(84) Designated Contracting States: BE DE FR GB NL SE (30) Priority: 11.04.1983 US 19830483923 (71) Applicant: AT&T Corp. New York, NY 10013-2412 (US)	(72) Inventors: LEE, Edward, Ashford Berkeley, CA 94709 (US) SHAW, David, Goodwin Middletown, NJ 07748 (US) (74) Representative: Lawrence, Brian Richard  Western Electric Company Limited 5, Mornington Road Woodford Green Essex IG8 OTU Woodford Green Essex IG8 OTU (GB)