私有综合服务网络（PISN）是一种专用网络，用于提供各种通信服务，如语音、数据和视频。PISN可以在组织内部或跨组织之间使用。为了实现这些服务，PISN需要一种信令协议，以便在不同的网络之间进行通信。

ISO/IEC 20114:2004标准主要介绍了呼叫请求补充服务。呼叫请求是指用户向网络发出请求，以建立一个呼叫。呼叫请求补充服务是指在呼叫请求过程中提供的额外服务，例如呼叫等待、呼叫转移和呼叫保持等。

ISO/IEC 20114:2004标准定义了呼叫请求补充服务的语法和语义，以及与呼叫请求补充服务相关的消息和参数。该标准还定义了呼叫请求补充服务的操作和行为，以及与呼叫请求补充服务相关的错误和异常情况。

ISO/IEC 20114:2004标准的目的是确保不同网络之间的互操作性，并提供一种标准化的方法来实现呼叫请求补充服务。该标准还可以帮助网络供应商和用户更好地理解呼叫请求补充服务的功能和操作。

相关标准
- ISO/IEC 11572:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call transfer supplementary service
- ISO/IEC 11574:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call waiting supplementary service
- ISO/IEC 11582:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call hold supplementary service
- ISO/IEC 13870:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call completion supplementary service
- ISO/IEC 13871:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call offer supplementary service