ISO/IEC 13869:2003 PDF

Overview

ISO/IEC 13869:2003 specifies the inter-exchange signalling protocol to support the Call Transfer supplementary service (SS-CT) at the Q reference point between Private Integrated Services Network eXchanges (PINXs) in a Private Integrated Services Network (PISN). Part of the PSS1 (QSIG) family, this is a stage 3 protocol specification that defines how a user can transform two of their calls (at least one answered) into a new call between the two other parties. The standard builds on basic circuit-switched call control and generic supplementary-service procedures and provides ASN.1 operation definitions, state machines, message sequences, and conformance requirements.

Key Topics

• Scope and applicability: Protocol for SS-CT between PINXs interconnected to form a PISN; relevant to enterprise PBX interoperability.
• Protocol layering: Operates on top of the basic circuit-switched call control (ISO/IEC 11572) and uses generic supplementary-service procedures (ISO/IEC 11582).
• Transfer methods: Defines transfer by join (mandatory) and transfer by rerouting (optional, with fall-back to join).
• ASN.1 operations: Call-Transfer operations (identify, initiate, setup, active, complete, update, etc.) are defined in ASN.1 for consistent encoding.
• State machines and procedures: States for Transferring, Primary, Secondary and Transit PINXs and detailed signalling procedures, including interactions with Transit PINXs.
• Service interactions: Specifies how SS-CT interacts with other supplementary services and additional network features (e.g., call forwarding, name presentation, completion-on-busy/no-reply, path replacement).
• Conformance & testing: Protocol Implementation Conformance Statement (PICS) proforma and annexes (ASN.1 definitions, SDL models, message examples).
• Timers and parameters: Timers (T1–T4) and parameterization are included to ensure interoperable behaviour (values specified in the standard).

Applications

• Enterprise telephony and PBX vendors implementing QSIG-compatible call transfer across multi-vendor PINXs.
• Systems integrators and network architects designing or validating inter-PBX signalling in a PISN.
• Interoperability testing labs and implementers verifying conformance using the PICS proforma and message sequence examples.
• Gateways and gateway-PINXs handling interworking between private networks and public ISDNs or legacy non-ISDN networks.

Related Standards

• ISO/IEC 11572 - basic circuit-switched call control
• ISO/IEC 11582 - generic supplementary-service procedures
• ISO/IEC 13865 - stage 1/2 service specification for Call Transfer
• ISO/IEC 13868 / 13873 / 13874 - related QSIG supplementary services (name identification, call diversion, path replacement)
• ETS 300 387 - method for service specification

Keywords: ISO/IEC 13869:2003, Call Transfer, SS-CT, PISN, PINX, Q reference point, QSIG, signalling protocol, ASN.1, PICS, PBX interoperability.