本标准的目的是根据美国国家标准和本文确定的ITU-T建议，定义评估提供电信服务的综合业务数字网络（ISDN）性能的综合基础。本标准:（a）定义了用于描述ISDN承载业务性能的参数；（b）规定了ISDN性能参数的最坏情况目标。这些参数和目标适用于电路模式和分组模式ISDN承载业务。除非本标准中另有说明，定义的参数和规定的目标适用于使用单个B通道和/或D通道的ISDN服务；本标准的计划修订将涉及其他ISDN承载业务（例如，n x 64 kbit/s）。ISDN参数值的实际测量方法将在本标准的计划补充中规定。

The purpose of this standard is to define a comprehensive basis for assessing the performance of Integrated Services Digital Networks (ISDNs) providing telecommunication service in accordance with the American National Standards and ITU-T Recommendations identified herein. This standard: (a) defines parameters that 5 be used to describe the performance of ISDN bearer services and (b) specifies worst-case objectives for the ISDN performance parameters. The parameters and objectives are applicable to circuit mode and packet mode ISDN bearer services. Unless noted otherwise in this standard, the defined parameters and specified objectives apply to ISDN services using a single B channel and/or D channel; planned revision to this standard will address other ISDN bearer services (e.g., n x 64 kbit/s). Practical methods for measuring ISDN parameter values will be specified in a planned supplement to this standard.