ISO/IEC 19460:2003 PDF

Overview - ISO/IEC 19460:2003 (Single Step Call Transfer, SS-SSCT)

ISO/IEC 19460:2003 defines the inter‑exchange signalling protocol for the Single Step Call Transfer supplementary service (SS‑SSCT) at the Q reference point between Private Integrated services Network eXchanges (PINXs) in a Private Integrated Services Network (PISN). This stage‑3 specification (QSIG/PSS1 family) describes how a user (A) converts an existing call with user (B) into a new call between user (B) and user (C) when user A has no prior call with C. The standard builds on basic circuit‑switched call control and generic supplementary‑service procedures and includes signalling interactions with other services and additional network features (ANFs).

Key topics and technical requirements

• Scope and conformance: Specifies requirements for PINX behaviour to conform to SS‑SSCT; conformance is checked via a Protocol Implementation Conformance Statement (PICS) proforma (Annex A).
• Reference architecture: Operates at the Q reference point defined in ISO/IEC 11579‑1 and forms part of the PSS1/QSIG protocol family.
• Protocol layering: SS‑SSCT signalling runs on top of basic circuit‑switched call control (ISO/IEC 11572) and reuses generic supplementary‑service control procedures (ISO/IEC 11582).
• Operations and encoding: Messaging and operations are defined using ASN.1 encoding (with ASN.1 definitions and imported modules included in annexes).
• Roles and states: Defines functional roles (Transferring, Transferred, Transferred‑To, Rerouting, Transit PINX) and state machines for each role.
• Procedures and interactions: Detailed signalling procedures for initiating, rerouting and completing a single‑step transfer, plus interaction rules with many other supplementary services and ANFs (e.g., call forwarding, name presentation, advice of charge).
• Timers and parameters: Protocol timers (T1, T2, T3) and operational parameter guidance are included to ensure interoperable behaviour.
• Implementation artefacts: Annexes provide message sequence examples, SDL representations, ASN.1 and PICS templates to support implementation and testing.

Applications and who uses it

• Enterprise telephony vendors / PBX manufacturers implementing QSIG-compatible inter‑PBX signalling for enterprise voice networks (PISNs).
• System integrators and network architects designing multi‑site private networks that require transparent call transfer across PINXs.
• Test labs and conformance bodies using the PICS and annex examples to validate interoperability.
• Telecom product teams ensuring correct interactions with supplementary services (call forwarding, call transfer, call diversion) and gateway interworking with public ISDNs or non‑ISDN networks.

Related standards

• ISO/IEC 19459 (stage 1/2 SS‑SSCT functional model and information flows)
• ISO/IEC 11572 (basic circuit‑switched call control)
• ISO/IEC 11582 (generic supplementary‑service procedures)
• ISO/IEC 11579‑1 (PISN reference configuration)
• ETS 300 387, ITU‑T Q.950 and related QSIG/PSS1 specifications

Keywords: ISO/IEC 19460, SS‑SSCT, Single Step Call Transfer, QSIG, PISN, PINX, inter‑exchange signalling, ASN.1, supplementary service.