ETSI EN 301 029-1 Broadband Integrated Services Digital Network (B-ISDN); Signalling System No.7; B-ISDN User Part (B-ISUP); Part 1: Overview of the B-ISDN network node interface signalling capability set 2, step 1 [ITU-T Recommendation Q.2721.1 (1996)]

standard by European Telecommunications Standards Institute, 04/01/1998