COMMUNICATION STATE RECOGNITION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a communication state recognition method in which a communication state of a terminal is recognized, without making a call to the terminal so as to conduct efficient communication. SOLUTION: A packet link is formed between exchanging devices comprising a group, when contained extension terminals are changed from an opened state into a called state or vice versa, the change is informed to another exchanging device through a DT packet and each exchanging device displays it to each contained extension terminal so as to inform another extension terminal capable of an incoming call to each extension terminal in the group, so as to eliminate an originating call to extension terminals which are incapable of an incoming call.