OENORM EN 300646-1 V 4.2.2
Integrated Services Digital Network (ISDN) - Signalling System No.7 - Digital cellular telecommunications system (Phase 2) - Application of ISDN User Part (ISUP) version 2 for the ISDN-Public Land Mobile Network (PLMN) signalling interface - Part 1: Protocol specification (GSM 09.12 version 4.2.2)