在数据通讯中指呼叫用户的动作，或在产生呼叫时所需的操作，或由两个通讯站连接起来实现的有效使用。

In data communications, the action performed by the calling party, or the operations necessary in making a call, or the effective use made of a connection between two stations.

youdao

在数据通讯中指呼叫用户的动作，或在产生呼叫时所需的操作，或由两个通讯站连接起来实现的有效使用。

In data communications, the action performed by the calling party, or the operations necessary in making a call, or the effective use made of a connection between two stations.

youdao