European digital cellular telecommunications system (Phase 2) - Unstructured Supplementary Service Data (USSD) - Stage 2; English version ETS 300549:1995
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)
Digital Enhanced Cordless Telecommunications (DECT) - Global System for Mobile communications (GSM) - DECT/GSM Interworking Profile (IWP) - General description of service requirements - Functional capabilities and information flows
