scope:

The present document specifies the second version of the Integrated Services Digital Network (ISDN) - Global System for Mobile communications (GSM) Public Land Mobile Network (PLMN) signalling interface. The present document is applicable to the interconnection of PLMN and ISDN. The ISUP interface defined is the trunk signalling interface between the PLMN and the ISDN. It is assumed that the interface between PLMN and ISDN can occur at any point in a national network, provided that the exchange in the national network has this ISDN-PLMN signalling interface. This signalling interface is based on ISUP version 2 (as given in ETS 300 356-1 to ETS 300 356-19 ([1] to [18])). The functionality in the GSM system is based on GSM Phase 2.