TOLL_CALL_KILLER

Published:2009/7/14 6:50:00 Author:May | From:SeekIC

Prevents unauthorized direct long-distance dialing through repeater autopatch from areas where 1 must be dialed ahead of desired out-of-town phone number. Based on simultaneous detection of 350-Hz component of dial tone and 1209- and 697-Hz tones assigned to 1 in Touch-Tone system. Circuit requires only three 567 tone decoders, 7402 quad gate, and either transistor or relay for controlling autopatch. Article covers installation and operation.-W. J. Hosking, Long Distance Call Eliminator, 73 Magazine, April 1976, p 44-45.



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