The present document specifies a set of technical requirements for Digital Enhanced Cordless Telecommunications (DECT) Fixed Parts (FP) supporting connection@ via an ISDN interface@ to a network supporting terminal mobility. The standard covers the requirements necessary for the support of Cordless Terminal Mobility (CTM) Phase 1 (Part 1) and for the support of the DECT access to GSM via ISDN interfaces (Part 2). In both of these scenarios@ the FT is connected to the network via the alpha interface@ as specified in [11]. NOTE: For CTM phase 1@ the Portable Part (PP) requirements are specified in the Generic Access Profile (GAP) [9]. The present document specifies the interworking procedures between the Digital Enhanced Cordless Telecommunications (DECT) air interface and the mobility management protocols defined for Integrated Services Digital Network (ISDN) interfaces. The ISDN Access Profile (IAP)@ ETS 300 434-2 [16]@ specifies the requirements for the support of ISDN services. Apart from the mobility management procedures@ that are covered in the present document@ the IAP includes interworking specifications for the support of basic call.