Modern telecommunication networks are going to be a so called Broadband Integrated Services Digital Network (B-ISDN), which can support transmission of multimedia information such as text, image, video, audio.

• 传统的通信网络是以语音信号传输为主的，今天的通信网络正在向能够支持文本、图象、视象、声音等多媒体信息传输的宽带综合业务数字网(B-ISDN)方向发展。