scope:

This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Communication, Networks and Systems Interconnection (ECMA), 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. This particular EN specifies the Q interface Signalling protocol (QSIG) for use at the Q reference point in support of the Call Priority Interruption and Call Priority Interruption Protection Supplementary Services. The QSIG protocol is known as "Private integrated Signalling System no.1" (PSS1) in International Standards.