Telephone line access control
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United States of America Patent
Stats
-
Aug 28, 1990
Grant Date -
N/A
app pub date -
Jan 13, 1988
filing date -
Jun 28, 1985
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A telephone line access control or call-barring unit operates on the monitor-and-clear principle to achieve selective call barring. The unit monitors dialled pulses being sent to an exchange, and recognizes a four-digit security number or authorization code intended to be known only to authorized users for bypassing the call-barring function. It also recognizes one or more two-digit or three-digit access codes for programming the call-barring unit to enter various different call-barring modes. The programmablity is purely in response to dialled numbers from any telephone connected to that particular line, and includes the option of changing the authorization code.
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