PURPOSE: To perform display by means of pilot lamps and sending out of various kinds of tone signals by means of a loudspeaker, etc., in accordance with the operation of dial keys and function keys, by installing a discriminating means which discriminates that whether or not an output of the dial keys is data indicating a previously fixed test request.

CONSTITUTION: A detecting section DKD, discriminating section JUD, and control section CT are installed to an enclosed path and outputs of a hook-switch HS2 and dial key PDK are given to the detecting section DKD. When the output of the dial key PDK is detected by the detecting section DKD on the assumption that an on-hook condition is set and the discriminating section JUD discriminates the output of the dial key PDK as data indicating test request after discriminating the output in accordance with the detected output of the discriminating section DKD, the discriminated result is given to the control section CT and the section CT is set to the operating condition. When the control section CT is actuated, the section CT sounds a loudspeaker SP by means of a tone signal from an oscillator OSC through an amplifier A by controlling the oscillator OSC and a switching circuit SW2 and, on the other hand, lights or flashes pilot lamps of a display circuit LDP by controlling them.