The present document specifies the technical characteristics to be provided by terminal equipment which is capable of connection to an Integrated Services Digital Network (ISDN) and which uses Digital European Cordless Telecommunications (DECT) for network access. The cordless transmissions for such terminal equipment operate within the frequency band 1 880 MHz to 1 900 MHz. A DECT terminal equipment comprises two elements, referred to as a Fixed Part (FP) and a Portable Part (PP). The objective of the present document is to ensure air-interface interoperability between a FP and PP following the DECT/ISDN Interworking Profile (IWP) (see note 2), where these parts are capable of 3,1 kHz telephony applications, and where the FP is connected to the ISDN in order to provide ISDN services (according to TBR 3  and TBR 4 ), over the DECT air interface. For functional parts of a FP, that are terminal equipment and which are declared to conform to the basic Common Technical Regulations (CTRs) for DECT (see note 1) and to the DECT/ISDN IWP, the requirements of the present document shall apply, in addition to the attachment requirements for the appropriate ISDN. The requirements of the present document are also applicable for the complete set of functionality of a PP declared to conform to the DECT/ISDN IWP. For a PP, the present document is in addition to the basic CTRs for DECT (see note 1).