Foreword This European Standard (Telecommunications series) has been produced by ECMA on behalf of its members and those of the European Telecommunications Standards Institute (ETSI)@ and is now submitted for the ETSI standards One-step Approval Procedure. The present document is one of a series of standards defining services and signalling protocols applicable to Private Integrated Services Networks (PISN). The series uses the Integrated Services Digital Network (ISDN) concepts as developed by ITU-T and conforms to the framework of standards for Open Systems Interconnection (OSI) as defined by ISO/IEC. The present document specifies the signalling protocol for use at the Q reference point for Private User Mobility call handling additional network features ANF-PUMI and ANF-PUMO. The protocol defined in the present document forms part of the PSS1 protocol (informally known as QSIG). The present document endorses an International Standard@ ISO/IEC 17878.