Overview
ISO/IEC 18056:2012 defines XML Schema Definitions for Computer Supported Telecommunications Applications (CSTA) Phase III. It specifies an XML protocol implementing the services defined in ISO/IEC 18051 and provides an alternative to the ASN.1 protocol in ISO/IEC 18052. The standard documents the underlying request/response model, association management, service/template notation, required conformance (PICS), and includes examples of CSTA XML encodings and optional transport mechanisms such as CSTA over SIP (uaCSTA).
Key topics and technical requirements
- XML protocol mapping: Schema-based encodings for the full set of CSTA Phase III services, enabling XML messaging for call control and event reporting.
- Request/response model: Formal description of interactions, request/response protocol requirements, and cross-referencing of event reports.
- Association management: Defines implicit and explicit application associations for session/connection management.
- XML template and top-level schema: Template description and top-level schema elements for consistent XML message structure.
- Parameter types and identifiers: Definitions for switching function objects, device identifiers, call & connection identifiers, connection states, and status reporting.
- Service families: Capability exchange, system services (registration, status), monitoring services, snapshot services, and comprehensive call control services and events (make call, hold, transfer, conference, clear, etc.).
- Conformance and PICS: Static and dynamic conformance requirements, PICS (Protocol Implementation Conformance Statement) rules, and XML tag options (long/short tags and transformations).
- Transport options: Support for uaCSTA (CSTA over SIP) as an optional transport mechanism.
- Security & extensions: Sections on security parameters, common extensions, error values, and empty/null element handling.
- Examples and encodings: Practical XML examples illustrating CSTA message encodings.
Practical applications & who uses it
ISO/IEC 18056:2012 is used by:
- Telecom equipment vendors and PBX/UC system manufacturers implementing CSTA interfaces with XML.
- CTI (Computer Telephony Integration) developers building client applications, softphones, and middleware that control calls and receive events.
- Contact center and workforce optimization vendors integrating call control, monitoring, and call-detail-record (CDR) exports.
- Network integrators and managed service providers who require standard XML-based interoperability across multi-vendor environments.
Practical uses include real-time call control, monitoring and reporting, capability negotiation, device management, billing/charge info export and CDR generation using standard XML schemas.
Related standards
- ISO/IEC 18051 - CSTA service definitions (services this XML maps to)
- ISO/IEC 18052 - ASN.1 protocol option (alternative to this XML protocol)
- ECMA-323 (equivalent specifications referenced for tag options and encodings)
Keywords: ISO/IEC 18056, CSTA Phase III, XML Schema, telecommunications, XML protocol, uaCSTA, call control, CTI, PICS, ISO/IEC 18051.