ISO/IEC 19459:2001 PDF

Overview - ISO/IEC 19459:2001 (Single Step Call Transfer, SS-SSCT)

ISO/IEC 19459:2001 defines the Single Step Call Transfer (SS-SSCT) supplementary service for Private Integrated Services Networks (PISN). The standard specifies the service behaviour, stage 1 (feature principles and capabilities) and stage 2 (functional model and information flows). SS-SSCT enables a user (A) to transform an existing call between A and B into a new call between B and C where A has no prior call with C. The result: B and C communicate directly and A is released from the connection.

Keywords: ISO/IEC 19459:2001, Single Step Call Transfer, SS-SSCT, PISN, Private Integrated Services Network, supplementary service, call transfer, functional model, information flows.

Key topics and technical requirements

• Service definition and scope
  • Applicability to basic services defined in ISO/IEC 11574 (circuit-mode 64 kbit/s bearer services).
  • SS-SSCT may be invoked for incoming or outgoing active calls.
• Stage 1 (feature principles)
  • General description of invocation, normal and exceptional procedures.
  • Behaviour on incomplete transferred-to numbers (option for B to complete C’s number).
  • Rules for when the original connection is released (e.g., on ringing or on connect).
• Stage 2 (functional model & information flows)
  • Identification of Functional Entities (FEs) involved (references to FE1..FE7 and basic call FEs such as Call Control/CCA).
  • Definition of information flows (SETUP, RELEASE, REPORT, etc.) and example sequences.
  • Allocation of FEs to physical locations and detailed FE actions/behaviour.
• Interactions
  • Defined interactions with other supplementary services and ANFs (e.g., CLIR restrictions applied to transferred calls; SS-CT and SS-SSCT are mutually exclusive during invocation).
• Conformance
  • To claim conformance a stage 3 specification (signalling protocols and equipment behaviour) must be provided to implement stage 1/2 requirements.

Applications - who uses ISO/IEC 19459:2001

• Telecom equipment manufacturers and PBX/PISN vendors implementing call transfer features.
• Systems integrators and network architects designing private telephony networks.
• Protocol and signalling engineers writing stage 3 signalling specifications for PISN interchanges.
• Test labs and QA teams validating functional behaviour and interoperability of SS-SSCT implementations.

Practical uses: implementing one-step transfer in enterprise private networks, ensuring correct presentation/restriction of calling/connected identifiers during transfers, and guiding functional allocation in multi-node PISN exchanges.

Related standards

• ISO/IEC 11574 (basic call services)
• ISO/IEC 11571 (addressing)
• ISO/IEC 11579-1 (PINX)
• ISO/IEC 13865 / 13869 (call transfer specs & signalling)
• ETS 300 387 (method for specification of services)
• ITU-T I.210, Z.100 (service description, SDL)

This standard is essential for clear, interoperable implementation of Single Step Call Transfer in private integrated service networks.