| 摘要 |
PURPOSE:To transmit a control signal through communication channels so that the control signal can be transmitted through another channel even when a channel gets out of order and communications can be performed. CONSTITUTION:When the No. of a called office is selected by keying-in on a keyboard 35, a controller 36 selects a vacant communication channel and sends a control signal to the called office through a control signal sending section (any one of 40, 41, and 42) connected with th vacant channel. At the called office, comparators 37-39 always monitor the communication channels and, when the control signal comes to a vacant chnnel, read the control signal and compare the control signal with the own office No. at the controller. When the control signal coincides with the own office No., the comparators 37-39 output a response signal and connect the vacant channel with a talking circuit 43 by closing one of talking switch sections 40-42. At the calling office the talking switch is closed simultaneously with the confirmation of the response and the talking circuit 43 is connected. |
