1980-11-25
1982-11-09
Brigance, Gerald L.
179 18DA, H04M 166
Patent
active
043586406
ABSTRACT:
A telephone security device has a code signal recognition means for storing two sets of variables, one of which governs the current operating mode of the system, and the other of which comprises first and second predetermined multiple-digit numerical code numbers responsive to proper inputs for producing first and second output signals, respectively. These output signals control a mode register means which has two stable states. In one state, the mode register means responds to the first output signals of the code signal recognition means to enter into its other state, thereby rendering the inhibiter means inoperative and allowing any number of outgoing calls to be made. The mode register means remains in this other state even following disconnection of a subsequently made call. However, the mode register means responds to the second output signal of the code signal recognition means to re-enter its one state, in which case the inhibiter means prevents the successful completion of certain calls as determined by the current operating mode of the system. The code signal recognition means includes an electrical alterable read-only memory ("EAROM") which may be continually reprogrammed without requiring a disassembly of the telephone set.
REFERENCES:
patent: 3851109 (1974-11-01), Downs et al.
patent: 3872260 (1975-03-01), Oatis
patent: 3985972 (1976-10-01), Rolin et al.
patent: 4046965 (1977-09-01), Kontomerkos
patent: 4099033 (1978-07-01), Murray
patent: 4153937 (1979-05-01), Poland
patent: 4188508 (1980-02-01), Rogens et al.
"Data Traffic in PABX's", International Switching Symposium Record, Willret, 1972, published by IEEE.
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