DIN ETS 300661-1:2000-05
Действует
Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; Direct Dialling In (DDI) supplementary service - Part 1: Protocol specification [ITU-T-Recommendation Q.2951, clause 1 (1995), modified] (Endorsement of the English version ETS 300661-1:1997 as German Standard)
