By analyzing the definition,interface,services and terminal standards of the ISDN,this paper discusses a plan for realizing narrowband ISDN in S1240 J serial machines and proposes a rudimentary scheme for building ISDN in our country. ?

• 通过分析综合业务数字网（ISDN）的定义、接口、业务和终端标准，讨论了在S1240J系列机上实现窄带ISDN的方案，提出了建设我国ISDN网的初步建议。