| 摘要 |
PURPOSE:To secure the perfect connection and protection of the secret, by connecting the recall terminal which is decided previously in response to the called memory to the central processor. CONSTITUTION:A telephone call is given to central processor 80 from maintenance center 20 via exchange circuit network 30 and then rung off after a fixed time. Then this telephone call from center 20 is detected by call detecting circuit 62 in access right checking circuit 60 and at the same time stored in called memory FF63. After this , automatic return telephone circuit 61 transmits the telephone number of center 20 which is known previously, i.e., the telephone number of the called terminal which is decided previously to network control unit 40 via number information signal group 43 and in response to the called memory. And the second call is given to center 20. When the call is connected, connection end signal 44 is turned on. And then data set ready signal 52 is turned on. Accordingly, output 67 is produced at AND circuit 65 to start the communication between processor 80 and center 20. |
