PURPOSE: To send a response message by voice synthesis from the beginning to a caller at the time of closing by loading the reset to the voice synthesis when a calling signal is detected in a moment when a telephone line is closed after detection and giving a starting pulse to the voice synthesis after a prescribed delay after the closing.

CONSTITUTION: When a switch 1 for operation is set to the position of AUTO, by the charging current conducted when the right edge of a capacitor C2 is grounded through the switch 1 for the operation, a momentary L level and a sound part 2 start a starting terminal; the inverse of ST of a sound synthesizing part 2 through a diode D1. When a calling signal enters, synchronization is executed to the calling signal, a resetting pulse is generated and the resetting pulse is given to a voice synthesizing part 2. Namely, the calling signal is detected by a photocoupler 6, the output is smoothed by a diode D4 and a capacitor C5, and while the calling signal enters, a transistor TR-1 is turned on and the pulse of the L level is given through a diode D5 to a resetting terminal; the inverse of RST of the voice synthesizing part.