| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic switching system for a telephone line which can use the period during no telephone communication for transmission of a signal from a monitor camera, without incurring no hindrance to telephone communication in a monitoring apparatus through the monitor camera using a telephone line placed in an in-house. SOLUTION: A transmitting unit 1 connecting a telephone 5 and a monitor camera 3 is connected via an in-house line 8 to a receiving unit 2 connecting an external line 9 and a monitoring TV. A signal from the monitor camera 3 is transmitted over the in-house line 8 in the normal operation. The in-house line 8 is used for communication between the telephone 5 and the external line 9, only when the transmitting unit 1 detects off-hook at the telephone 5 and when the receiving unit 2 detects a ringing tone signal from the external line 9. COPYRIGHT: (C)2004,JPO
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