US3727007A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone security device
Assignee: Commercial Communications Ltd
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Filing: 1970-11-18
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Granted: 1973-04-10
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Expires: 1990-11-18
Abstract
Abstract In order to prevent the unauthorized use of dial-type telephone to make long distance calls, the security device of the present invention is connected to the wall-box at which the telephone cord is connected to the telephone Company''s wiring. In position, it permits the effective dialing of up to say eight digits, and then prevents the effective dialing of any further digits until the telephone handset has been replaced and removed. The number of digits permitted will depend upon the type of installation, eight digits being used in a PABX: in a PABX a long distance direct dialed call requires the dialing of 9-1- and seven digits, i.e. 9 digits in all, and any attempted call is aborted in the absence of the last digit. A pulse-group counter stops the transmission of enough pulse-groups to make a distance-directdialed call. By the added subject matter of the present application, a zero detector circuit is added to disable all attempts to make long distance calls through the telephone operator.
Inventors
- 👤 R Catlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:23
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/66; H04M1/677
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
235 words
A security device suitable for use with a dial-type telephone set having a handpiece, a cradle in or on which the handpiece rests when not in use, and a rotary signalling dial, the device being adapted to restrict the use of the dial to the effective dialing of a series of digits no greater in number than a predetermined number and to prevent the effective dialing of zero to call a central station operator to make long distance calls, comprising: a. connecting leads by which the device can be connected to terminals carrying dialed pulses from the signalling dial; b. pulse grouping means adapted to transform groups of received separate dialing pulses each into a group pulse by distinguishing between interpulse timing periods and intergroup timing periods; c. group-pulse counting means; d. zero detecting means comprising an electrical circuit adapted to ascertain whether digit dial pulses applied to it represent a dialed zero, and arranged to produce an output indicative of that fact; e. digit selection means preset to select from the group pulses either the first or the second dialed digit and to apply the dialing pulses of that selected digit to the zero detecting means; and f. call aborting means arranged to prevent the effective transmission of dialing pulses both when the group-pulse counting means has reached a predetermined count and when the zero detecting means provides an output indicative of zero detection.
Claim 2
Dependent Claim
235 words
A security device suitable for use with a dial-type telephone set having a handpiece, a cradle in or on which the handpiece rests when not in use, and a rotary signalling dial, the device being adapted to restrict the use of the dial to the effective dialing of a series of digits no greater in number than a predetermined number and to prevent the effective dialing of zero to call a central station operator to make long distance calls, comprising: a. connecting leads by which the device can be connected to terminals carrying dialed pulses from the signalling dial; b. pulse grouping means adapted to transform groups of received separate dialing pulses each into a group pulse by distinguishing between interpulse timing periods and intergroup timing periods; c. group-pulse counting means; d. zero detecting means comprising an electrical circuit adapted to ascertain whether digit dial pulses applied to it represent a dialed zero, and arranged to produce an output indicative of that fact; e. digit selection means preset to select from the group pulses either the first or the second dialed digit and to apply the dialing pulses of that selected digit to the zero detecting means; and f. call aborting means arranged to prevent the effective transmission of dialing pulses both when the group-pulse counting means has reached a predetermined count and when the zero detecting means provides an output indicative of zero detection.
Claim 3
Dependent Claim
21 words
The security device claimed in claim 1, wherein switch means are provided by which the said predetermined count can be varied.
Claim 4
Dependent Claim
68 words
The security device claimed in claim 1, wherein an internal battery is arranged to bias a transistor switch to a conductive condition, and the line voltage is used to bias that transistor switch to a non-conductive condition, whereby when the cradle switch of the telephone set closes, the consequent fall in line voltage permits the battery to make the transistor switch conductive so energizing the group-pulse counting means.
Claim 5
Dependent Claim
22 words
The security device claimed in claim 3, wherein the line voltage normally applies through a diode charging current to the said battery.
Claim 6
Dependent Claim
42 words
The security device claimed in claim 1, wherein the call aborting means comprise a switch arranged to shunt the terminals carrying the said dialed pulses from the signalling dial, and effective to attenuate those pulses so severely as to render them ineffective.
Claim 7
Dependent Claim
55 words
The security device claimed in claim 1, wherein the call aborting means comprise a switch arranged in series with one of the pulse-carrying leads connected to the said terminals, this switch being of the ''''normally closed'''' type but being opened to prevent the transmission of pulses once the predetermined number of pulses has been received.
Claim 8
Dependent Claim
37 words
The security device claimed in claim 1, wherein the call aborting means are associated with a switch by which they can be rendered effective even before any pulses are received, whereby no digits can be effectively dialed.
Claim 9
Dependent Claim
53 words
The security device according to claim 1, wherein a rotary lock having a plurality of positions at each of which the lock key can be removed is arranged to determine the setting of the security device in accordance with the orientation of the rotary lock at the time that the key is removed.
Claim 10
Dependent Claim
29 words
The security device according to claim 8, wherein the rotary lock also has an ''''open'''' position in which it permits removal of an access cover from the security device.
References Cited (Backward Citations)
US3566042A
Cited
US3553382A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-09 | 1976-10-09 | 1977-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-09 | 1980-10-09 | 1981-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-09 | 1984-10-09 | 1985-04-10 | $7700.00 | Window Closed / Lapsed |