| 摘要 |
<p>An internet telephony system including plural client computers, each connecting to a switching unit and a server computer connected to the client computers with internet and storing users' phone numbers. The switching unit connects to a typical telephone and connects to a line of PSTN. The client computer sends its IP address to the server during the client connecting the internet. A user inputs a telephone number of a person whom the user wants to call. The server informs an IP address corresponding to the telephone number sent by the user's client computer. The user's client computer confirms whether the IP address is accessible. When the IP address is accessible, the switching unit provides a connection of the telephone via internet. When the IP address is not accessible, the switching unit provides a connection of the telephone via a line of PSTN.</p> |
