To define the TBR for DECT/ISDN portables with the aim of achieving inter-operability between DECT/ISDN portables and GAP or GSM infrastructure. To investigate which additional essential requirements to TBR 022 have to be considered for type approval of DECT/ISDN portables. Deliverable = TBR or Harmonised standard for DECT/ISDN. Edition 2 involves adding essential requirements to DECT/ISDN Intermediate System Configuration (Edition 1 only covered the End System Configuration).