Integrated Services Digital Network (ISDN) - Signalling System No. 7 - Transaction Capabilities (TC) version 2 - Part 1: Protocol specification (ITU-T Recommendations Q.771 to Q.775 (1993), modified); English version ETS 300287-1:1996
Integrated Services Digital Network (ISDN) - Digital Subscriber Signalling System No. one (DSS1) protocol - Signalling network layer for circuit-mode basic call control - Part 1: Protocol specification [ITU-T Recommendation Q.931 (1993), modified]
Integrated Services Digital Network (ISDN) - Signalling System No.7 - ISDN User Part (ISUP) version 3 interactions with the Intelligent Network Application Part (INAP) - Part 1: Protocol specification [ITU-T Recommendation Q.1600 (1997), modified]