ETSI EN 300 356-16
ETSI EN 300 356-16
Integrated Services Digital Network (ISDN); Signalling System No.7 (SS7); ISDN User Part (ISUP) version 4 for the international interface; Part 16: Call Hold (HOLD) supplementary service [ITU-T Recommendation Q.733, clause 2 (1993) modified]
standard published 07/01/2001 by European Telecommunications Standards Institute
