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IP-TELEPHONY

The Internet fundamentally changes our representations about methods of communication. Though telephone networks and data networks coexisted within decades, they developed independently from each other. The IP-telephony unites them in a uniform network which offers a power and economic communications facilities. Tens companies worldwide offer solutions for IP-telephony. They combine a voice and the data in one network and offer cheap international and Long-distance calls and the whole set of communication services to any user.

General principle of action of IP-telephony is those: from one side a server is connected to telephone lines and can unite with any telephone of the world. From other side a server is related to the Internet and can contact with any computer in the world. The server receives the standard telephone signal, digitizes it, considerably compresses, breaks into packets and sends over the Internet to destination. For packages, comings from a network on a telephone server and included in the telephone line, an operation takes place in a reverse order. An input of a signal in a telephone network and its output occur practically simultaneously, that allows to provide high-grade conversation.

To carry out communication with the help of telephone servers, operators of service should have on a server in those places where and whence bells are planned. Cost of such communicationis much lower than cost of a call on usual telephone lines. This difference for the international negotiations is especially great.

The technology of a call of the subscriber by means of a IP-telephony practically does not differ from traditional. The person on an ordinary telephone set instead of "eight" dials local number of the nearest telephone server and hears the voice invitation with the offer to dial the number the called subscriber (or all over again to enter identification number if it is necessary). After dialing the system of a IP-telephony (through the second server) connects the consumer to the phone of the called subscriber. If conversation may not be held, ringing by a voice will be informed on the reason (for example, " the called number is busy ", "incorrectly dialed up", etc.) the System also transmits ringing subscriber such signals as "call", "is busy"), and so forth Thus, ringing hears habitual signals of a telephone network.