ETSI EN 300 356-12 English Printed Edition English PDF 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]

standard published 07/01/2001 by European Telecommunications Standards Institute