Completion of Calls on No Reply (CCNR) is an ISDN supplementary service offered to the calling user.

无应答时呼叫的完成(CCNR)是一种向主叫用户提供的ISDN补充业务。

youdao

Completion of Calls on No Reply (CCNR) is an ISDN supplementary service offered to the calling user.

无应答时呼叫的完成(CCNR)是一种向主叫用户提供的ISDN补充业务。

youdao