PURPOSE: To allow a doorphone (interphone) outdoor equipment provided to a gatedoor or the like to call selectively a resident of a parent household or a resident of a child household in a multi-zone housing in which, e.g. the parent household and the child household are divided in prescribed zones.

CONSTITUTION: A visitor depresses a pushbutton switch 5a or 5b of an opposite party to be visited. A pulse generating circuit 6a(6b) detects switch-on of the pushbutton switch 5a or 5b and provides an output of a call signal with a predetermined frequency when the switch-on is detected. Which pushbutton switch is depressed is discriminated from the call signal because of the difference of the frequency. A modulation/demodulation circuit 8 modulates the call signal and sends the modulated signal to doorphone indoor equipments 11a, 11b. The doorphone indoor equipments 11a, 11b generate the call tone when the modulated call signal is a call signal with a preset frequency to send the presence of a visitor to a resident.