Automatic telephone-line disconnect system
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsEdwin C. Myers, Theodore J. Rauen
Life of this patent
Estimating the term…
Abstract
A telephone disconnect system having a current-sensitive relay which automatically operates to electrically connect the telephone lines to the telephone network when the cradle switch of the telephone is closed, and which automatically operates to electrically disconnect the telephone lines from the telephone network when the cradle switch is open thus providing protection against the use of a cradled telephone as a clandestine listening device.
Claims20
An automatic telephone line disconnect adapted to be coupled to a telephone network, which disconnect operates to prevent the use of a cradled telephone as a clandestine listening device, comprising:
- electrical lines selectively connected with respect to said telephone network and with respect to each other;
- at least two energy storage means normally coupled to said electrical lines adapted to be connected with respect to said telephone network and with respect to each other;
- and
- a power supply operative to charge said energy storage means.
An automatic multiline telephone disconnect system which operates to prevent the use of a cradled telephone as a clandestine listening device, and which is capable of operating over a wide range of telephone line currents, comprising:
- a telephone network;
- a plurality of pairs of electrical lines selectively connected with respect to said network;
- normally disabled amplification means operatively associated with said network to be controlled by line current flowing through said lines and said network when the network is in an operating condition;
- energy storage means selectively coupled to said amplification means;
- normally disabled first current-sensing means coupled to said amplification means and operative to maintain said network and said lines in a normally open circuit relationship when said amplification means is disabled;
- a normally open cradle switch in circuit relationship with said network and operable to be placed in closed circuit relationship with said network and said energy storage means;
- a plurality of line-selector switches each one operatively associated with a respective one of said plurality of pairs of electrical lines to enable the selective connection of a predetermined line pair to said network;
- each of said line-selector switches movable to be selectively coupled to said energy storage means;
- whereby when said cradle switch and one of said line-selector switches are closed said first current-sensing means is activated so as to couple together said network and a respective pair of said electrical lines to enable electrical energy to pass through.
In combination:
- a telephone network;
- at least a pair of conductors selectively coupled to said network from outside said network;
- and
- automatic telephone line disconnect means coupled to said telephone network for selectively and physically disconnecting each one of said conductors from said network.
An automatic multiline telephone disconnect adapted to be coupled to a telephone network, which operates to prevent the use of a cradled telephone as a clandestine listening device, and which is capable of operating over a wide range of telephone line currents, comprising:
- a plurality of pairs of electrical lines selectively connected with respect to said network;
- normally disabled amplification means operatively associated with said network to be controlled by line current flowing through said lines and said network when the network is in an operating condition;
- energy storage means selectively coupled to said amplification means;
- normally disabled first current-sensing means coupled to said amplification means and operative to maintain said network and said lines in a normally open circuit relationship when said amplification means is disabled;
- a normally open cradle switch in circuit relationship with said network and operable to be placed in closed circuit relationship with said network and said energy storage means;
- a plurality of line-selector switches each one operatively associated with a respective one of said plurality of pairs of electrical lines to enable the selective connection of a predetermined line pair to said network;
- each of said line-selector switches movable to be selectively coupled to said energy storage means;
- whereby when said cradle switch and one of said line-selector switches are closed said first current-sensing means is activated so as to couple together said network and a respective pair of electrical lines to enable electrical energy to pass therethrough.
Dependencies are inferred from the claim text.