| 摘要 |
PURPOSE:To secure the office call even from the office extension telephone set (OPX) added to the key telephone with use of the extension counter circuit. CONSTITUTION:When the connection is desired for the main wire 14 to OPX12 which is an exclusive telephone, OPX12 calls out key telephone 13 via extension 15 to request for the trunk connection. Telephone 13 catches extension circuit 2 after confirming the idle state of the main wire and then gives dialing with addition of the special number to the head of the extension number of the OPX. Extension counter circuit 3 identifies the special number and then starts trunk connection circuit 9 within extension circuit 5 through trunk connection control circuit 4 as well as drives called control circuit 6. Thus, the signals given from bell power source 8 are transmitted to OPX12. With reply of OPX12, OPX12 is connected to main wire 14 via contact 10. Thus OPX12 is ready for transmission of the main wire. In the case of incoming of the main wire, OPX12 can also be connected to the main wire through the same operation of telephone 13. |
