(19)

(11)

EP 0 561 888 A1

(12)

(43) Date of publication: 29.09.1993 Bulletin 1993/39 (21) Application number: 92900538.0 (22) Date of filing: 11.12.1991

(51) International Patent Classification (IPC):  H04Q 3/ 00( . ) H04L 12/ 56( . ) H04L 12/ 18( . ) (86) International application number: PCT/AU1991/000574 (87) International publication number: WO 1992/010898 (25.06.1992 Gazette 1992/14)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE (30) Priority: 12.12.1990 AU 19900003901 (71) Applicant: AUSTRALIAN AND OVERSEAS TELECOMMUNICATIONS CORPORATION LIMITED Sydney, NSW 2000 (AU)	(72) Inventors: ANIDO, Gary, J. Narwee, NSW 2209 (AU) FOLLETT, Douglas, James Carlingford, NSW 2118 (AU) (74) Representative: Meddle, Alan Leonard, et al  FORRESTER & BOEHMERT Franz-Joseph-Strasse 38 D-80801 München D-80801 München (DE)