IP TELEPHONE DEVICE, IP TELEPHONE SYSTEM AND COMMUNICATION METHOD

PROBLEM TO BE SOLVED: To facilitate speech communication using a system different from an extension call in an IP telephone device. SOLUTION: An IP telephone system comprises a plurality of IP telephone devices 101-106 each capable of performing speech communication by an intercom speech communication which automatically activates a voice input output means and is in a speech communication state. In this system, information indicating the intercom speech communication is set in "INVITE request" defined in a communication protocol from a transmitter side IP telephone device 101 of a transmitter side, the information is sent to a receiver side IP telephone device 102 of a receiver side, and when the IP telephone device 102 of the receiver side detects the "INVITE request" in which the information indicating the intercom speech communication is set, the voice input output means is automatically activated to enable speech communication with the IP telephone device 101 of the transmitter side. COPYRIGHT: (C)2005,JPO&NCIPI