Think of the telephone network as the model. 让我们以电话网为模型来考虑这个问题。
A term applied to a data transmission carried on the public switched telephone network and initiated by dialing the telephone number of the receiving station. 应用于普通开关电话网数据传输上的术语,指拨通某接收站的电话号码就能访问该系统的性质和动作。