| 摘要 |
PURPOSE:To report the existence of incoming to a terminating subscriber without interrupting the call and display the originating subscriber's number by transmitting a code of incoming during call and a number code as a control signal from an exchange to a digital telephone set when incoming exists during the call of the digital telephone set. CONSTITUTION:A channel is set between a subscriber 13 and a ringing tone sending trunk 9. A transmission instruction of the code of incoming during call is sent to a control signal transmitting and receiving circuit 8. The control signal transmitting and receiving circuit 8 transmits the code of incoming during call as the control signal to a digital telephone set 1 through a subscriber's circuit 6. A control circuit 3 in the digital telephone set 1 receives the code of incoming during call, and a display device 5 of incoming during call is used to display the incoming. Further, a central processing unit 10 transmits the originating subscriber's number to the digital telephone set 1 through the control signal transmitting and receiving circuit 8 with the number code corresponding to this number. The control circuit 3 receives a series of number codes and uses an originating subscriber's number display device 4 to display the originating subscriber's number. |
