Symbol,Reference itu-t88,[ITU-T Q.761-4 (1988)] itu-t92+,[ITU-T Q.761-4 (1992)] ansi88,"[ANSI T1.113-1988 (""Signaling System Number 7 (SS7) - ISDN User Part"")]" ansi00,[ANSI T1.113-2000] etsi121,"[ETS 300 121 (""Integrated Services Digital Network (ISDN)"" Application of the ISDN User Part (ISUP) of CCITT Signalling System No. 7 for international ISDN interconnections (ISUP version 1).)]" etsi356,"[ETS 300 356-1 (""Integrated Services Digital Network (ISDN)""; Signalling System No.7; ISDN User Part (ISUP) version 2 for the international interface.)]" ttc87,[JT-Q761-4(1987-1992)] ttc93+,[JT-Q761-4(1993-)]