| 摘要 |
An Internet switch box connects between a telephone set and a public switched telephone network (PSTN) line, the latter of which is used both for PSTN telephone conversations and for connection to an Internet service provider (ISP). The switch box contains hardware and embedded software for establishing a connection to an ISP and for Internet telephony. When two users, each having an Internet switch box connected to the telephone set, wish to have an Internet telephony conversation, one calls the other over the PSTN. When they agree to an Internet telephony conversation, they signal their Internet switch boxes, by pressing either buttons on the switch boxes or certain keys on the telephone keypads, to switch to Internet telephony. The switch boxes disconnect the PSTN call and connect to their ISPs. Once the switch boxes are on the Internet, they contact each other through a server which supplies Internet protocol (IP) addresses of switch boxes, and the users continue their conversation by Internet telephony. The users can also prearrange to call each other solely by Internet telephony, in which case they do not need to talk to each other over the PSTN.
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