ETSI EN 300 356-8 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 8: User-to-User Signalling (UUS) supplementary service [ITU-T Recommendation Q.737, clause 1 (1997) modified]

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