Method and apparatus for controlling access to a communication system
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United States of America Patent
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-
Oct 16, 1990
Grant Date -
N/A
app pub date -
Apr 4, 1988
filing date -
Apr 4, 1988
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Subscriber units operating within a communication system are selectively addressed and required to solve a 'Puzzle' generated by a central device (controller) of a two-way communication system. The 'Puzzle' comprises one or more digital words and an operand, which provides instructions to the subscriber unit as to how to generate an answer. The subscriber units cannot anticipate either the occurrence nor the content of a particular 'Puzzle'. All subscriber units (both authorized and unauthorized) must return an answer to the 'Puzzle' or they may be denied access to the two-way communication system. Also, unauthorized subscriber units may be detected when the central device receives multiple answers to a 'Puzzle'.
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