Telephone call restricting apparatus

Details Telephone call restricting apparatus Telephone call restricting apparatus

1978-08-21

1980-02-12

Brown, Thomas W.

H04M 166

Patent

active

041885082

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.

REFERENCES:
patent: 3920936 (1975-11-01), Mogtader

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