TELEPHONE COMMUNICATION METHOD CAPABLE OF RELATING A TELEPHONE TERMINAL AND A SPEECH CHANNEL IP ADDRESS AT THE TIME OF CALL CONNECTION

摘要

A telephone communication method capable of promoting the efficient use of the limited number of IP (Internet Protocol) addresses is disclosed. When a call is originated on a first telephone terminal, a first gateway accommodating the terminal accesses a DNS (Domain Name System) server via a UDP (User Datagram Protocol) channel of Internet or Intranet. The first gateway inquires the DNS server of the IP address of a second gateway accommodating a telephone terminal to be called, using an office number assigned to the second telephone terminal as a host name. The DNS server returns the IP address of the second gateway to the first gateway via the UDP channel. In response, the first gateway selects its own IP address for speech transfer and sends a call connection request to the second gateway on a TCP (Transmission Control Protocol) channel of Internet. On receiving the request, the second gateway determines whether or not the second telephone terminal is busy, and selects the IP address for speech transfer if it is idle. The IP address selected is returned to the first gateway in the form of a response message. As a result, a connection is set up between the two telephone terminals.