ETSI TS 100 976 English Printed Edition English PDF Digital cellular telecommunications system (Phase 2+) (GSM); 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 version 7.1.1 Release 1998)

standard published 07/01/1999 by European Telecommunications Standards Institute