PURPOSE: To obtain a stable operation by using a filter so as to cut off only a frequency component of a push-button telephone signal in a message signal outputted from a message signal generating means and outputting the result to a line.

CONSTITUTION: A filter 12 cuts off only a push-button telephone signal frequency component in a message signal outputted form a message signal generating means 11 and outputs the result to an output terminal T. Thus, even when a message signal is bypassed to a reception side as a side tone, since no push- button telephone signal frequency component is included in the side tone, a push-button telephone signal detection means 15 does not make mis-detection. Thus, a correct push-button telephone signal from a line is always detected to make a stable operation.