私有综合服务网络（PISN）是一种专用的通信网络，用于在组织内部提供各种通信服务。PISN可以提供多种服务，包括语音、数据和图像等服务。其中，电路模式64 kbit/s承载服务是PISN中最基本的服务之一。

ISO/IEC 11574:2000标准规定了电路模式64 kbit/s承载服务的服务描述、功能能力和信息流。该标准主要包括以下内容：

1. 服务描述：该部分描述了电路模式64 kbit/s承载服务的基本特性和服务质量要求。其中，服务质量要求包括语音、数据和图像等服务的时延、抖动、丢包率等指标。

2. 功能能力：该部分描述了电路模式64 kbit/s承载服务的功能能力，包括呼叫建立、呼叫保持、呼叫转移、呼叫释放等功能。

3. 信息流：该部分描述了电路模式64 kbit/s承载服务的信息流，包括呼叫建立过程中的信令流程、语音、数据和图像等信息的传输流程等。

ISO/IEC 11574:2000标准的实施可以帮助组织建立高效、可靠的PISN电路模式64 kbit/s承载服务，提高组织内部的通信效率和质量。

相关标准
- ISO/IEC 11572:1995 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Circuit-mode 64 kbit/s bearer services — Service description, functional capabilities and information flows — Group call supplementary service
- ISO/IEC 11573:1995 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Circuit-mode 64 kbit/s bearer services — Service description, functional capabilities and information flows — Completion of calls to busy subscribers
- ISO/IEC 11576:1995 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Circuit-mode 64 kbit/s bearer services — Service description, functional capabilities and information flows — Call transfer supplementary service
- ISO/IEC 11577:1995 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Circuit-mode 64 kbit/s bearer services — Service description, functional capabilities and information flows — Call waiting supplementary service
- ISO/IEC 11578:1995 Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Circuit-mode 64 kbit/s bearer services — Service description, functional capabilities and information flows — Call hold supplementary service