Telephone call restricting apparatus
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United States of America Patent
Stats
-
Feb 12, 1980
Grant Date -
N/A
app pub date -
Aug 21, 1978
filing date -
Aug 21, 1978
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A telephone call restricting apparatus for preventing toll calls and including circuitry for sequentially decoding the signals representing each digit of a telephone number, storing the first seven decoded digit signals in binary and converting the stored signals into decimal number signals, a comparator for comparing the decimal number signals corresponding to the appropriate digits of the telephone number with permissable local central exchange digits stored in a programmed memory device, a 90 detector and 0/1 detector for detecting long distance calls, an 800 detector and a 555 detector for detecting toll free long distance calls and logic responsive to both the comparator and the detectors and operative to abort unapproved toll calls.
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