Abstract: A telephone exchange apparatus which selectively sets an interface circuit connecting a communication line adapted to connect a telephone terminal and having a communication control function for the telephone terminal, and adapted to communicate between the communication line and another communication line by applying a voltage necessary for operation to the interface circuit includes a display which displays information representing an operating state of the interface circuit, in the interface circuit, a detector which detects whether the voltage applied to the interface circuit is more than a reference value, and generate a detection result, in the interface circuit and a controller which controls the display to display the information representing the operating state based on the detection result.

Abstract: The game system comprises an image display device; an operation input device issuing a signal corresponding to an operation of a player; a mode select device for selecting one mode between a breeding mode in which a breeding game is prepared and a competition mode in which a competition game is prepared; a breeding game control device for controlling a progress of the breeding game, and a competition game control device.

Abstract: This invention enables the key telephone system to send a busy tone to a party calling on a main extension number when a telephone call to the main extension number is received when a pseudo extension number is in use. The receiving mode is memorized in the memory of the main unit. When a telephone call to the main extension number is received when the pseudo extension number is in use, a busy tone can be sent to the calling party on the main extension number. According to this invention, the calling party thus knows that the key telephone set, which is the destination of his call, is busy.