DIN ETS 300668-1:1997-09
Действует
Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; User-to-User Signalling (UUS) supplementary service - Part 1: Protocol specification [ITU-T Recommendation Q.2957, clause 1 (1995), modified]; English version ETS 300668-1:1996