本国际标准规定了服务描述和控制方面，包括功能和性能 可由专用综合业务支持的标准化电路模式承载业务的信息流 网络（PISN）。 本国际标准包括以下基本服务: _电路模式64kbit/s无限制8kHz结构化承载业务类别； _可用于语音信息传输的电路模式64kbit/s 8kHz结构化承载业务类别； _电路模式64 kbit/s 8 kHz结构化承载服务类别，可用于3.1 kHz音频信息传输。 PISN应支持上述三种承载业务中的至少一种，以符合本国际标准。 本国际标准的范围不包括: _通话建立时的服务协商， _通话中的服务变更，以及 _单向服务。 本国际标准包括提供相当于以下公共ISDN功能的可选程序 补充服务:子地址和多用户号码。 注1:可与64 kbit/s电路交换承载业务结合使用的补充业务和其他承载业务 本国际标准中的规定在其他标准中处理。 注2:服务规范基于发布时可用的相应公共ISDN服务的相关信息 本国际标准的发布。 注3——ITU-T将子地址和多用户号码视为补充业务。 注4:对于从公共ISDN进入PISN的呼叫，应考虑使用公共ISDN的直接拨号补充业务 作为PISN基本服务的一部分。 注5:使用主叫线标识表示和连接线标识表示补充业务 公共ISDN用于从公共ISDN或向公共ISDN获取呼叫的起始号码或连接号码，被视为 PISN中的基本服务。 注6:用户向网络提供（明示或暗示）自己的号码（原始号码或连接号码） PISN向另一个网络提供始发号码或连接号码是网络基本服务的一部分 PISN，而非主叫线路标识表示和连接线路标识表示补充业务的一部分。 这些补充服务仅涉及从网络向被服务的PISN用户呈现号码。

This International Standard specifies the service description and control aspects, including functional capabilities and information flows, of standardised circuit-mode bearer services which may be supported by a Private Integrated Services Network (PISN). This International Standard includes the following basic services: _ Circuit-mode 64 kbit/s unrestricted 8 kHz structured bearer service category; _ Circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for speech information transfer; _ Circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3,1 kHz audio information transfer. A PISN shall support at least one of the above three bearer services to conform with this International Standard. The scope of this International Standard does not include: _ the negotiation of service at call establishment time, _ the change of service during a call, and _ unidirectional services. This International Standard includes optional procedures for the provision of functions equivalent to the following public ISDN supplementary services: Subaddress and Multiple Subscriber Number. NOTE 1 - Supplementary services and other bearer services which can be used in conjunction with 64 kbit/s circuit switched bearer services specified in this International Standard are dealt with in other standards. NOTE 2 - Service specifications are based on information concerning the corresponding public ISDN service available at the time of publication of this International Standard. NOTE 3 - ITU-T treat Subaddressing and Multiple Subscriber Number as supplementary services. NOTE 4 - The use of the Direct Dial In supplementary service of a public ISDN for calls incoming to a PISN from a public ISDN is regarded as part of the basic services in a PISN. NOTE 5 - The use of the Calling Line Identification Presentation and Connected Line Identification Presentation supplementary services of a public ISDN for obtaining the Originating Number or the Connected Number of a call from or to a public ISDN is regarded as part of the basic services in a PISN. NOTE 6 - The provision (either explicitly or implicitly) by the user to the network, of its own number (Originating Number or Connected Number), and the provision of an Originating Number or a Connected Number by a PISN to another network is a part of the basic services in a PISN and not a part of the Calling Line Identification Presentation and Connected Line Identification Presentation supplementary services. Those supplementary services are concerned only with the presentation of the number from the network to the served PISN user.