ISO/IEC 20161:2001

Overview

ISO/IEC 20161:2001 defines how the QSIG signalling system (PSS1) is used at the C reference point between a Private Integrated Services Network Exchange (PINX) and an Interconnecting Network (ICN) to achieve interoperable digital signalling. The standard prescribes a functional profile combining base standards, selected options and parameter values so equipment from different vendors and public or private service providers can interwork. The scope is limited to the C reference point at a separate interface and typically treats the ICN as a virtual transit PINX. Annexes include a Requirements List (RL) and a profile-specific Implementation Conformance Statement (ICS).

Key topics and technical requirements

• Interoperability focus: Mandatory capabilities are defined in Annex A (RL) and conformance is determined by correctly implementing those capabilities and the ICS (Annex B).
• Protocol stack coverage:
  • Layer 1 (Physical) - physical and electrical characteristics including Basic Access (2xB+D) and Primary Rate (2048 kbit/s: 30xB+D; 1544 kbit/s: 23xB+D).
  • Layer 2 (Data Link) - data link procedures consistent with ISDN/Q.921.
  • Layer 3 (Network) - addressing/routing, basic call procedures, segmentation/reassembly, channel identification, sub-addressing, cause codes, bearer services and progress indicators.
• Generic Functional Protocol (GF) - support for supplementary services and signalling procedures to carry additional features between PINX and ICN.
• Supplementary services & ANFs - profiles and procedures for Advice of Charge (AOC), Call Diversion (CFB/CFNR/CFU), Call Transfer (CT), Path Replacement (PR), Call Interception (CINT), Transit Counter (TC), Private User Mobility (PUMCH), Wireless Terminal Call Handling (WTMCH), Single Step Call Transfer (SSCT), Call Priority Interruption (CPI), and related keypad/feature key procedures.
• Normative references - aligned with ISDN and PISN standards (e.g., ISO/IEC 11572, 11582), ITU-T I.430/I.431, Q.920/Q.921 and ECMA family documents.

Applications and who uses it

• Telecom equipment manufacturers implementing PINX interfaces for corporate telecommunication networks (CNs).
• VPN and ICN service providers deploying QSIG over C reference point for private network interconnection.
• Network integrators and system architects designing multi-vendor PISN interconnections.
• Conformance and interoperability test labs creating PICS/ICS test cases.
• Enterprise IT/telecom teams planning interoperable PBX/PINX connectivity to external interconnecting networks.

Related standards

• ISO/IEC 11572, 11582 (PISN signalling)
• ISO/IEC TR 14475 (PISN architecture and scenarios)
• ITU‑T I.430 / I.431 (physical layer for ISDN)
• Q.920 / Q.921 (data link layer)

Keywords: QSIG, PINX, C reference point, ICN, Private Integrated Services Network, interoperability, PSS1, ISDN, virtual transit PINX, corporate telecommunication network.