E BYTE/D BYTE COMMUNICATION EQUIPMENT

PURPOSE:To prevent communication disturbance to another route by starting communication after confirming the unused state of a line by a transmitter with respect to the transmission equipment of a synchronizing digital hierarchy. CONSTITUTION:A first transmission equipment 1 out of first and second transmission equipments 1 and 4 facing each other is provided with a transmission request transmission part 14 which confirms transmission permission before communication and sends request contents and a device number to a transmission destination, a transmission request detecting part 15 which recognizes transmission permission to confirm the unused state of the line and sends the transmission permission to the transmission request transmission part 14, and a display part 16 on which the transmission permission is displayed, and each of the second transmission equipment 4 and first and second repeaters 2 and 3 is provided with circuits having the same functions as the transmission request transmission part 14, the transmission request detecting part 15, and the display part 16 provided in the first transmission equipment 1, and communication between devices is started after confirmation of the unused state of the line.