全球通信 global communications

灵活性 flexibility

端到端的数字连接 end-to-end digital connectivity

开放网络 open network

语声编码 voice encoding

综合业务数字网 integrated services digital network

系统结构 infrastructure

国际标准化组织International Organization for Standardization

通信载体 communication carriers

传输媒体 transmission medium

接口设备 interface equipment

带宽限制 bandwidth limitation

交换设备 switching equipment

语音编码 voice encoding

脉码调制 pulse code modulation

基本接入 basic access

综合业务数字网 the integrated services digital network

国际标准化组织 the International Organization for Standardization

由于传输媒体导致的质量下降 degradation due to the transmission medium

4kHz话路中所固有的带宽限制 bandwidth limitations inherent in a 4kHz voice channel

标准化的接口 standardized ports

脉（冲编）码调制 pulse code modulation

数字通信 digital communication

ISDN的标准和系统结构 ISDN standards and system architecture

全球通信 global communication

数字技术的逐步应用 progressive application of digital technology

共同通信载体 public communication carriers

高质量 enhanced quality

大量的接口设备 substantial quantity of interface equipment

带宽的限制 bandwidth limitations

端到端的数字连接 end-to-end digital connectivity

语音编码技术 voice encoding techniques

基本接入信令速率 basic access signaling rate

统一的接入 universal access