ETSI EN 300 356-19 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 19: Three-Party (3PTY) supplementary service [ITU-T Recommendation Q.734, clause 2 (1996) and implementors guide (1998) modified]

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