Abstract: The emergency call such as Enhanced 911 call or the like is also originated through an exchange such as PBX (Private Branch Exchange). In this case, the identification information such as the extension number of the extension telephone terminal connected to the PBX should be transmitted to a network corresponding to the emergency call. For the extension telephone terminal, it is necessary to unhook or to capture an arbitrary line by the line key, before inputting the dial data “911”. Independent of the capture of arbitrary line, the PBX searches a vacant line connected to the network corresponding to the emergency call, captures the vacant line, transmits the identification information such as the extension number, and switches over and connects the extension telephone terminal from the line captured by the terminal to the vacant line.