本国际标准规定了适用于以下情况的补充业务（SS）单步呼叫转移（SSCT） 由专用综合业务网（PISN）支持的各种基本业务。ISO/IEC中规定了基本服务 11574 SS-SSCT是一种补充业务，使SSCT用户a能够在用户a和用户a之间转换现有呼叫 B进入用户B和用户C之间的新呼叫，由此用户a在呼叫之前没有与用户C建立呼叫 转移 根据ETS 300 387中描述的方法，补充业务规范分三个阶段生成。这 国际标准包含SS-SSCT的第1阶段和第2阶段规范。第1阶段规范（第6条） 指定一般功能原则和功能。 第2阶段规范（第7条）确定了功能实体 参与补充服务以及它们之间的信息流。

This International Standard specifies the Supplementary Service (SS) Single Step Call Transfer (SSCT), which is applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ISO/IEC 11574. SS-SSCT is a supplementary service that enables an SSCT user, user A, to transform an existing call between user A and user B into a new call between user B and a user C whereby user A does not have a call established with user C prior to call transfer. Supplementary service specifications are produced in three stages, according to the method described in ETS 300 387. This International Standard contains the stage 1 and stage 2 specifications of SS-SSCT. The stage 1 specification (clause 6) specifies the general feature principles and capabilities. The stage 2 specification (clause 7) identifies the Functional Entities involved in the supplementary service and the information flows between them.