QSIG Protocol Stack -- "C" Source Code

QSIG source code software and QSIG device drivers will accelerate development and conformance testing of your QSIG product. TA good source code software QSIG protocol stack provides the fastest path to market-ready QSIG products for manufacturers worldwide.  QSIG is a variant of ISDN, and is sometimes called PSS1 (Private Signaling System 1), and is sometimes incorrectly referred to as PSS-1,  PDSS1, or P-DSS1.  The QSIG source code library is sometimes called a "QSIG stack" or "QSIG signaling stack".

A good ISDN software development toolkit is available in source code and is architected for applications, both embedded and host-based, in which performance and code size are important.

An embedded ISDN SDK has available interfaces to several standard preemptive and non-preemptive real-time operating systems and non-real time operating systems, including ATMOS, Linux, MQX, Nucleus Plus, OSE, pSOS, TsRITE*, VRTX, and VxWorks 

Integrated Systems Digital Network (ISDN) is a term that encompasses a large number of protocols, including Q.921/Q.931 Narrow-band ISDN (N-ISDN), Q.2931 Broadband ISDN (B-ISDN), Q.922/Q.933 Frame Relay and other protocols.  Usually when you hear ISDN, it means the N-ISDN set of protocols (e.g. Q.921, Q.931.)  QSIG is a type of ISDN.

Narrowband ISDN (N-ISDN) also two major Physical interfaces--the two B channel Basic Rate Interface (BRI) and the 23, 24 or 30 channel Primary Rate Interface (PRI).  T1 lines may be channelized into 24 DS0 channels, one of which is used for the D channel (the signaling channel).   A good QSIG protocol stack that supports both Network and User sides of QSIG and is available for both the Basic Rate Interface (2B+D) and the Primary Rate Interface (23B+D or 30B+D).   Most commonly, QSIG is supplied over an E1 as a 30B+D service.

The QSIG protocol stack is used for PBX to PBX communication, and is considered a "symmetrical" ISDN stack, that is, there is no User vs. Network side.  There is, however, an "A" and a "B" side (sometimes called a "master" and "slave" side) for the purpose of glare resolution, but this difference is much smaller than the Network and User side difference of Q.931.  Normally, any equipment that supports QSIG has the "A" or "B" side option configurable at run time, on a line-by-line basis.