| 摘要 |
PURPOSE:To give a control to the BCO originating connection given from a tester without killing the originating function of a subscriber to be tested, by giving a short circuit to the dial pulse contact and preventing the subsequent transmission of dial pulses. CONSTITUTION:An operator telephone circuit 1 is connected to a subscriber terminal to be tested through a dial contact 2 and then a line trunk. When a tester operates the BCO key, a connection is secured to an originating register trunk by a DC loop of the circuit 1. In this case, a normally opened contact 3 of the BCO key is closed by a testing device to give a short circuit to the contact 2. At the same time, a normally closed contact 4 of the BCO key is closed to form an AC loop and thus to prepare a monitor for subsequent originatings. |
