PURPOSE: To constitute a common subscriber network with one kind of common subscriber terminal equipments by allocating a different terminal equipment identification information signal to each of plural common subscriber terminal equipments in advance and identifying the terminal equipments in the timing of the terminal equipment identification information signal sent from each of common subscriber terminal equipment.

CONSTITUTION: A terminal identification information generating circuit 17 generates 4 kinds of identification signals 01, 02, 03, 04, which are assigned respectively as identification signals for common subscriber terminal equipments 10, 20, 30, 40. A terminal equipment information selection circuit 18 selects a signal, e.g. 01 from 4 kinds of identification signals generated by the terminal identification information generating circuit 17 and outputs the selected signal to an earth switch drive circuit 19. An earth switch 14 is activated synchronously with the terminal identification information signal 01 and the terminal identification information signal is sent to a ring line 4. An earth detection circuit 53 of a subscriber circuit 2 detects the terminal identification information signal and a subscriber control circuit 60 identifies which common subscriber terminal equipment hooks off.