Integrated Services Digital Network (ISDN) - Freephone (FPH) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 1: Protocol specification; English version ETS 300210-1:1996
Integrated Services Digital Network (ISDN) - Freephone (FPH) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol - Part 1: Protocol specification (Endorsement of the English version EN 300210-1 V 1.2.4 (1998-06) as German Standard)— 1 стр.
