ETSI GSM 09.07-1995 参见PRETS 300 604(版本4.10.0)(ETS 300 604)
Digital Cellular Telecommunications System (Phase 2+); General Requirements on Interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN) (GSM 09.07)