scope:

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 in support of the Short Message Service. 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 21990.