PRIVATE BRANCH EXCHANGE

A PBX causes an external line button of an incoming alert target terminal to flash on and off when there is an incoming alert from an external line. The PBX saves log data to a log data storage area of a memory in a case in which a non-answer monitoring time expires without an agent of the terminal pressing the external line button of terminal. Thereafter, the PBX extracts log data stored in log data storage area and transmits the log data to manager terminal in a case in which manager terminal indicates the acquisition of report information to the PBX.