PURPOSE: To perform communication requiring urgency quickly and accurately, by providing a discrimination signal generating function to discriminate the position of terminals for a handset at each terminal.

CONSTITUTION: A plurality of terminals consisting each of a main body 100, a handset 200, and a speaker 30 are connected as shown in Figure with displatching input lines 40, channels 50 and displatching output lines 60. A preamplifier 22 of the handset 200 is provided with a positive feedback circuit consisting of a bandpass filter 24 and a switch 25 and the said amplifier 22 acts like an oscillator for the generation of each terminal discrimination. The main body 100 is provided with band pass filter groups 13 and a driving circuit 14 for a lamp group 15 corresponding to the discrimination frequency from each terminal. After the switch 25 is operated at the handset 200, when calls with other terminals or simultaneous dispatching are made, the terminal making a call in the main body 100 is automatically displayed.