Controllable annunciator using ring signal
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United States of America Patent
Stats
-
Jul 11, 1989
Grant Date -
N/A
app pub date -
May 21, 1987
filing date -
May 21, 1987
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
This invention provides a central processing unit having read only memory for storing permanently the firmware and random access memory for storing the protocol which can be changed by user via the keyboard when need, which also has a detector for counting the ring signal inputted from the line and sending it to the CPU. When the count of the ring signal and the interval between the hang-up and dial are all met, the protocol stored in the RAM of the CPU and the control device enabled by the CPU via the output terminal send the tone signal to the ring apparatus for signaling the user.
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