ISO/IEC 18056:2004 specifies an XML protocol for the services described in ECMA-269, Services for Computer Supported Telecommunications Applications (CSTA)Phase III. ISO/IEC 18056:2004 provides an alternative protocol to the ASN.1-based protocol specified in ISO/IEC 18052 :2000. Clauses 5 to 8 inclusive describe the concepts underlying the request/response model, application association, notation and service, and a description of the template used in ISO/IEC 18056:2004. Clauses 9 to 26 inclusive contain CSTA-specific protocol details and forms the main part of this International Standard. Annex A specifies the PICS for this International Standard. Examples of CSTA XML encodings are provided in Annex B through Annex G.