Communication line control system

Abstract

Abstract PURPOSE:To attain switching of a communication line in spite of the absence of a terminating subscriber by executing switching from a private line to a public line and its reverse switching automatically when any one of the private and public communication lines is used for the mutual communication between two communication devices. CONSTITUTION:Modulation/demodulation devices 1, 2 connected to communication devices respectively are connected to line control devices 3, 4 respectively and both devices 3, 4 are coupled with each other by private lines 5, 6 and public lines 8-11 through an exchange 7. When an operation part 19 applies an indication to connect the public lines 8, 10 and 9, 11 to a control part 17a in the control device 3 at the data communication through the normal private lines 5, 6, the control part 17a applies a dial sending indication to a dial signal generating part 12, and when the device 3 is connected to the device 4 by sending the dial signal and the relays 15a, 16a are actuated, data communication parts 13 are connected, and after transmitting and receiving an identification code and a response code, are switched. When a line switching indication is applied from the operation part 19, a switching code is applied to the control device 4 through the lines 8, 10, and after detecting and responding the code, the lines 8, 10 are switched to the lines 5, 6.

Inventors

• 👤 Michinori Sugao
• 👤 菅生　道則

Bibliographic Details