ÖNORM EN 300356-12 V 4.2.1:2001-11
Действует
Integrated Services Digital Network (ISDN) - Signalling System No.7 (SS7) - ISDN User Part (ISUP) version 4 for the international interface - Part 12: Conference call, add-on (CONF) supplementary service [ITU-T Recommendation Q.734, clause 1 (1993) and implementors guide (1998), modified]
