To more securely and more speedily transmit an important simultaneous command by designating a satellite line and a ground line, transmitting the starting signals of the simultaneous commands to both lines and permitting a slave station to receive the simultaneous command by the line which previously receives the starting signal.

A satellite line 6 and a ground line a are designated to the line issuing the simultaneous command by the simultaneous command stand 2 of a control station 1. A simultaneous command controller 3 to which the command stand 2 is connected transmits the starting signal of the simultaneous command by giving a simultaneous or arbitrary time difference to a satellite line controller 9 and a ground line controller 10. In the slave station 8 receiving the simultaneous command, the line control part of the line receiving the starting signal earlier informs a main control part 11 of the termination of the simultaneous command and the main control part 11 connects the call path to a telephone set for receiving command 12 or FAX for receiving command 13. A response recognition signal and a command reception recognition signal are transmitted by the line which previously receives a simultaneous command starting signal or are transmitted by the satellite line 6 and the ground line 7 receiving the starting signal.