| 摘要 |
PURPOSE:To release a privacy state without executing transmitting/receiving of a signal by providing a function to cancel the said state by detecting the hook-on in the end-to-end privacy system. CONSTITUTION:In one line of respective telephones 1 and 2, respective one of hook information detecting parts 5 and 6 is inserted. If the call ends with the privacy state still lasting, the detecting parts 5 and 6 detect the cutting off of the loop current of the telephones 1 and 2 when the handset is hooked on, and cancels the privacy state of a privacy part 3.
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