US3715514A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone security device
Assignee: Dektor Counterintelligence and Security Inc
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Filing: 1970-10-07
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Granted: 1973-02-06
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Expires: 1990-10-07
Abstract
Abstract A device for preventing use of an on-hook telephone for eavesdropping or ''''bugging.'''' A voltage source is connected to the telephone line selector and hook switch through a diode matrix and sensing relay coil. When the telephone is ''''on-hook'''' (hook switch open) all conductors from the telephone instrument are short circuited together and are disconnected from the telephone conductors leading out of a private or secure area in which the telephone is located. The short circuiting is accomplished by a plurality of relays responsive to the condition of the sensing relay. When the instrument is off-hook the telephone conductors leading from the instrument are connected to the conductors leading from the area for normal conversational use. A lamp and photoresistor device is provided to isolate the annunciator from external conductors.
Inventors
- 👤 A Bell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:00
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/68
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
276 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductors external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing; first connector means associated with said housing for receiving a plurality of pairs of conductors entering the secure area; second connector means associated with said housing for receiving a plurality of pairs of conductors from a telephone instrument; a plurality of diodes connected to said pairs of conductors from the telephone instrument to form a plurality of individual circuit portions through the telephone instrument, each circuit portion being selectively completable through the telephone instrument and said second connector means by the line selector means and hook switch; first and second terminals within said housing connected to the ends of said circuit portion; a power supply; a sensing relay including a relay winding connected in series circuit relationship with said power supply between said first and second terminals, said sensing relay winding being energizable by completion of one of said individual circuit portions to close a normally open contact set; at least one additional relay each including a winding and a plurality of contact sets, each said winding being energizable upon energization of said sensing relay winding; each said contact set of said at least one additional relay being movable between a position in which all conductors from said instrument are connected to each other and a position in which said conductors at said first connector means are connected, in predetermined relationship, to said conductors at said second connector means.
Claim 2
Dependent Claim
276 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductors external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing; first connector means associated with said housing for receiving a plurality of pairs of conductors entering the secure area; second connector means associated with said housing for receiving a plurality of pairs of conductors from a telephone instrument; a plurality of diodes connected to said pairs of conductors from the telephone instrument to form a plurality of individual circuit portions through the telephone instrument, each circuit portion being selectively completable through the telephone instrument and said second connector means by the line selector means and hook switch; first and second terminals within said housing connected to the ends of said circuit portion; a power supply; a sensing relay including a relay winding connected in series circuit relationship with said power supply between said first and second terminals, said sensing relay winding being energizable by completion of one of said individual circuit portions to close a normally open contact set; at least one additional relay each including a winding and a plurality of contact sets, each said winding being energizable upon energization of said sensing relay winding; each said contact set of said at least one additional relay being movable between a position in which all conductors from said instrument are connected to each other and a position in which said conductors at said first connector means are connected, in predetermined relationship, to said conductors at said second connector means.
Claim 3
Dependent Claim
276 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductors external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing; first connector means associated with said housing for receiving a plurality of pairs of conductors entering the secure area; second connector means associated with said housing for receiving a plurality of pairs of conductors from a telephone instrument; a plurality of diodes connected to said pairs of conductors from the telephone instrument to form a plurality of individual circuit portions through the telephone instrument, each circuit portion being selectively completable through the telephone instrument and said second connector means by the line selector means and hook switch; first and second terminals within said housing connected to the ends of said circuit portion; a power supply; a sensing relay including a relay winding connected in series circuit relationship with said power supply between said first and second terminals, said sensing relay winding being energizable by completion of one of said individual circuit portions to close a normally open contact set; at least one additional relay each including a winding and a plurality of contact sets, each said winding being energizable upon energization of said sensing relay winding; each said contact set of said at least one additional relay being movable between a position in which all conductors from said instrument are connected to each other and a position in which said conductors at said first connector means are connected, in predetermined relationship, to said conductors at said second connector means.
Claim 4
Dependent Claim
276 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductors external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing; first connector means associated with said housing for receiving a plurality of pairs of conductors entering the secure area; second connector means associated with said housing for receiving a plurality of pairs of conductors from a telephone instrument; a plurality of diodes connected to said pairs of conductors from the telephone instrument to form a plurality of individual circuit portions through the telephone instrument, each circuit portion being selectively completable through the telephone instrument and said second connector means by the line selector means and hook switch; first and second terminals within said housing connected to the ends of said circuit portion; a power supply; a sensing relay including a relay winding connected in series circuit relationship with said power supply between said first and second terminals, said sensing relay winding being energizable by completion of one of said individual circuit portions to close a normally open contact set; at least one additional relay each including a winding and a plurality of contact sets, each said winding being energizable upon energization of said sensing relay winding; each said contact set of said at least one additional relay being movable between a position in which all conductors from said instrument are connected to each other and a position in which said conductors at said first connector means are connected, in predetermined relationship, to said conductors at said second connector means.
Claim 5
Dependent Claim
79 words
Apparatus according to claim 1 wherein the series circuit including said sensing relay and said power supply further includes a manually operable switch closable to temporarily energize said relay regardless of the completeness of any of said individual circuit portion; and at least one contact set operable by energization of said sensing relay winding to a closed position to maintain said relay energized if any of said individual circuit portion is complete when said manually operable switch is reopened.
Claim 6
Dependent Claim
201 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductOrs external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing external of and separate from the telephone instrument; first connector means associated with said housing for receiving conductors from a telephone instrument; second connector means associated with said housing for receiving conductors from a telephone instrument; relay circuit means within said housing for sensing an on-hook condition in said telephone instrument ; for providing a direct connection between each of said conductors from the telephone instrument whenever said telephone is in its on-hook condition; for disconnecting said conductors entering said secure area from conductors connected to the telephone instrument whenever the telephone is in its on-hook condition; and for conducting said conductors entering said secure area to said conductors from the telephone instrument when said telephone instrument is in its off-hook condition; an annunciator; and unidirectional energy transmission means connected to said selected ones of said conductors entering said secure area for actuating said annunciator in response to a call signal on said conductors.
Claim 7
Dependent Claim
201 words
A security apparatus for preventing undesired signal transmission from a telephone instrument in a secure area to telephone conductOrs external of the secure area, the telephone instrument being of the type having a hook switch and line selector means, the apparatus comprising the combination of a housing external of and separate from the telephone instrument; first connector means associated with said housing for receiving conductors from a telephone instrument; second connector means associated with said housing for receiving conductors from a telephone instrument; relay circuit means within said housing for sensing an on-hook condition in said telephone instrument ; for providing a direct connection between each of said conductors from the telephone instrument whenever said telephone is in its on-hook condition; for disconnecting said conductors entering said secure area from conductors connected to the telephone instrument whenever the telephone is in its on-hook condition; and for conducting said conductors entering said secure area to said conductors from the telephone instrument when said telephone instrument is in its off-hook condition; an annunciator; and unidirectional energy transmission means connected to said selected ones of said conductors entering said secure area for actuating said annunciator in response to a call signal on said conductors.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |