PURPOSE: To realize a remote control with no increment of the special control lines, by connecting the control terminal of the special monitor amplifier provided at the repeater station to the remote terminal of the unit to be controlled prior to the remote control action.

CONSTITUTION: Like the conventional special monitor amplifier, the normal talking is carried out between the transmitter microphone B and the telephone receiver A' and via the hybrids C and C'. And in case a remote control is given to the unit I to be controlled, a connection is given prior to the remote control action between the control terminal H of the special monitor amplifier provided at the repeater station and the remote terminal of the unit I. Then the control signal is sent to the order circuit J through the hybrid C from the control signal generating part D of the special monitor amplifier when the remote control is required.