The present document identifies the Interworking Functions (IWFs) and requirements for the interworking between a GSM PLMN and a Packet Switched Public Data Network/Integrated Services Digital Network (PSPDN/ISDN) for the support of packet services in GSM PLMNs. In the GSM PLMN context the packet services are associated with bearer services and are described in GSM 02.02. The generally defined GSM PLMN user-network access as defined in the respective GSM specifications (see references) forms the basis for defining the particularities for the provision of packet services to the GSM PLMN subscribers. Network internal interfaces for the support of packet services in the pan-European ISDN are defined in ETSI standards, which are also taken as a basis. User-network access and network internal interfaces are defined to provide the packet services.
