ETSI TS 129 007 English Printed Edition English PDF Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); General requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN) (3GPP TS 2

standard published 03/01/2001 by European Telecommunications Standards Institute