ISDN Protocol Stack -- "C" Source Code


ISDN Software

A good protocol stack implementing ISDN, available as source code software, and ISDN device drivers will accelerate development and conformance testing of your ISDN product, and will provide the fastest path to market-ready ISDN products for manufacturers worldwide. 

A good ISDN stack Multi-Level Precedence and Preemtion available.

Formerly known as Amlink or Amlink3, the ISDN stack has been fielded for over twenty years by hundreds of customers in thousands of products.

An ISDN stack is often referred to as a "Q.931 stack" or "Q.931 signaling stack" because Q.931 defines the basic rate ISDN and primary rate ISDN protocols.  ISDN is sometimes called Digital Signaling System 1, or DSS1.

Good Basic Rate and Primary Rate ISDN source code stacks should be proven and feature-rich software and should be available today. In addition to DSS1, AutoSPID, Autoswitch Detection, NFAS, and D-Channel Backup, a wide range of conformance tested worldwide switch variants should be available. Full NT and TE side support should be included.

BRI and PRI software solutions sould include source code for AutoSPID, Autoswitch Detection, NFAS, and D-Channel Backup in addition to DSS1 and other switch variants used worldwide.  Voice Supplementary Services, also referred to as Q.932 should also be available. 

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

A good embedded ISDN SDK will have currently 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), both Basic Rate ISDN (BRI) source code and Primary Rate ISDN (PRI) source code; 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.) 

PRI is used on a T1/E1/J1, and is often called "WAN protocol software", or "T1/E1/J1 signaling software" (as appropriate, often people are more specific and say "T1 signaling software" "E1 signaling software" or "J1 signaling software".)

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).    Non-Facilities Associated Signaling (NFAS) allows two or more T1 PRI lines to share a single D channel (this is especially useful on a T3, which can be channelized into 28 virtual T1 lines.)  E1 lines may be channelized into 32 DS0 channels, one of which is used for synchronization, one is used as the D channel (i.e. signaling channel) and the other 30 are used as bearer channels.  A good ISDN stack provides software that implements both Network and User sides of N-ISDN.

Q.931 ISDN defines both a network (NT) and a user (TE, or CPE) side, which define complementary parts of the ISDN state machine.  Many countries have their own variations of Q.931 signaling to meet their unique needs.  Most of the recent ISDN variants are "deltas", or variations, to the Euro-ISDN standard. 

A good ISDN stack should include a QSIG protocol stack: QSIG is a symetric Q.931 variant.

This Software is often called: 

  • T1 signaling stack
  • T1 protocol stack
  • T1 signaling source code
  • T1 WAN protocol software
  • E1 signaling stack
  • E1 protocol stack
  • E1 signaling source code
  • T1 WAN protocol software
  • J1 signaling stack
  • J1 protocol stack
  • J1 signaling source code
  • T1 WAN protocol software