本文介绍了国际电报电话咨询委员会(CCITT)关于ISDN的三个建议的主要内容。可以向用户提供的电信业务,乃是电信网的全部标准化工作的理所当然的出发点。电信网的必需功能只能由业务的要求中产生。各种业务愈早标准化,优越性就愈大,这会使跨越国界的通信可在相同的条件下实现。根据本文所提出的理由,CCITT在其全部ISDN工作中,对业务的统一定义和待提供的国际性业务的规范给予了高度优先的考虑。 This article describes the main contents of the three CCITT recommendations on ISDN. The telecommunications services that can be provided to subscribers are a matter of course for the full standardization of the telecommunications network. The necessary functions of the telecommunications network can only be generated by the requirements of the service. The sooner the various services are standardized, the greater the advantage, which will allow communications across national borders to be implemented under the same conditions. Based on the rationale presented in this paper, CCITT gives high priority to its uniform definition of business and the norms of international business to be provided throughout its work on ISDN.