Telephone communication method

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 (11), a first gateway (12) accommodating the terminal accesses a DNS (Domain Name System) server (16) via a UDP (User Datagram Protocol) channel (141) of Internet oir Intranet (13). The gateway (12) inquires the DNS server (16) of the IP address of a second gateway (14) accommodating a telephone terminal (15) to be called, using an office number assigned to the telephone terminal (15) as a host name. The DNS server (16) returns the IP address of the gateway (14) to the gateway (12) via the UDP channel (141). In response, the gateway (12) selects its own IP address for speech transfer and sends a call connection request to the gateway (14) on a TCP (Transmission Control Protocol) channel (142) of Internet. On receiving the request, the gateway (14) determines whether or not the telephone terminal (15) is busy, and selects the IP address for speech transfer if it is idle. The IP address selected is returned to the gateway (12) in the form of a response message (206). As a result, a connection is set up between the two telephone terminals 11 and 15.