The call forwarding sample demonstrates the call forwarding feature typically seen in public switched telephone networks, but it USES a SIP network.

Call Forwarding示例显示了访问转寄的特性，该特性一般见于公共交换电话网络，但是它使用了一个SIP网络。

youdao

As voice communications is the primary media of communication for human being, it plays a very important role from public switched telephone network to the third generation mobile communications.

话音是人与人之间交流的主要方式，从最早出现公共交换电话网络到现在的第三代移动通信，语音通信是其最基本的功能。

youdao

The number of lines and traffic of the Public Switched Telephone network (PSTN) network have also been decreasing.

公共电话交换网(PSTN)的线路和流量也在减少。

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When I travel I studiously avoid making and receiving voice calls over the public switched network because of the costs.

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Doesn't matter what kind of device the message is going to (wireline phones, mobile phones, PDAs or computers) or whether the message has to travel over the Internet or the public switched telephone network, for example.

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