Patent ID: 7463728

Claim:
A private branch exchange that can coordinate and manage connections for a plurality of extension phones, the private branch exchange comprising: a caller information detector for, when a call is received through a telephone line, obtaining caller information; a group incoming call table in which at least two extension numbers are correlated with an extension incoming call group number; a group incoming call log storage unit that stores a caller number obtained by the caller information detector; a first display controller for displaying a no answer message on a first display unit of each extension phone corresponding to the extension numbers correlated with the extension incoming call group number; a second display controller for displaying an incoming time and the caller number, which is extracted from the group incoming call log storage unit, on a second display unit of each of the extension phones corresponding to the extension numbers correlated with the extension incoming call group number; and a controller for, when the call received along the telephone line is for the extension incoming call group number, transmitting an incoming call signal to the extension phones corresponding to the extension numbers correlated with the extension incoming call group number and stores the caller number in the group incoming call log storage unit, wherein: when none of the extension phones to which the incoming call signal is routed is answered, the controller stores an incoming time and the caller number in the group incoming call log storage unit and the first display controller displays the no answer message on the first display unit of each of the extension phones corresponding to the extension numbers correlated with the extension incoming call group number, and when an incoming call log display request is received from at least one of the extension phones to which the incoming call signal is routed, the second display controller extracts the incoming time and the caller number from the group incoming call log storage unit and displays the incoming time and the caller number on the second display unit of the at least one extension phone and the first display controller cancels the display of the no answer message on the first display unit of each of the extension phones corresponding to the extension numbers correlated with the extension incoming call group number.