QSIG is originally developed by ECMA International, aiming to facilitate the interoperation among the communication platform from disparate vendors. QSIG has two layers, called BC (basic call) and GF (generic function). QSIG BC describes how to set up calls between PBXs. QSIG GF provides supplementary services such as line identification, call intrusion and call forwarding. QSIG will likely never rival each vendor’s private network protocols, but it does provide an option for a higher level of integration.
How does QSIG work
QSIG basically uses ROSE to invoke specific supplementary service at the remote PINX. The Remote Operations Service Element (ROSE) is the OSI service interface, specified by ITU-T, to conduct below tasks
1). provides remote operation capabilities
2). allows interaction between entities in a distributed application
3). upon receiving a remote operations service request, allows the receiving entity to attempt the operation and report the results of the attempt to the requesting entity
These ROSE operations are coded in a Q.931 FACILITY Information Element. Here a list of QSIG opcodes (more details, refer to http://en.wikipedia.org/wiki/QSIG):
To be continued