ITU Q.1912.5E:2008 Interworking Between Session Initiation Protocol (sip) And Bearer Independent Call Control Protocol (bicc) Or Isdn User Part (isup): Abstract Test Suite (ats) And Partial Protocol Implementation Extra Information For Testing (pixit) For Profiles A And B Describes the abstract test suite (ATS) and partial protocol implementation extra information for testing (PIXIT) for profiles A and B for interworking between session initiation protocol (SIP) and be