PURPOSE: To delete a tone/pulse switchable dialer by transmitting a tone signal from a tone dialer under the control of a control circuit, and transmitting a pulse signal from the control circuit at the time of power failure.

CONSTITUTION: A control circuit 1 detects power failure, and controls an LCR circuit 2, latch circuit 3, and tone dialer 4. Diodes D1 and D2 select two signals from the control circuit 1 and the LCR circuit 2 to a Tr circuit 6 for circuit closure by OR. Then, at the time of power supply, the tone signal is transmitted through the LCR circuit 2 and the latch circuit 3 from the tone dialer under the control of the control circuit 1, and the pulse signal is transmitted from the LCR circuit 2. At the time of power failure, the tone signal is also transmitted from the tone dialer 4 after the latch circuit 3 is made inoperative under the control of the control circuit 1, and the pulse signal is transmitted from the control circuit 1. Thus, a part of the LCR function is operated by the control circuit at the time of power failure, so that the tone/pulse switchable dialer can be deleted.