本标准是在综合业务数字网（ISDN）环境下定义和描述补充业务的系列标准之一。该补充服务可根据要求或订购安排提供。还包括该补充业务与其他ISDN业务的交互。该标准的目的是允许网络和用户拥有的电信设备之间的最大兼容性，以增加基于ISDN的能力的吸引力和实用性。

This standard is one of a series that defines and describes supplementary services within the context of an Integrated Services Digital Network (ISDN). This supplementary service may be made available on a demand or subscription arrangement. The interaction of this supplementary service with other ISDN services is also included. The purpose of the standard is to allow maximum compatibility among network- and user-owned telecommunications equipment in order to increase the attractiveness and usefulness of ISDN-based capabilities.