US4958371A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for determining when a telephone handset is off-hook
Assignee: Control Data Corp
•
Filing: 1988-04-19
•
Granted: 1990-09-18
•
Expires: 2008-04-19
Abstract
Abstract Apparatus in an automatic telecommunications system which communicates between a central location and at least one remote location over the switched telephone network, senses changes in loading of the telephone line which correspond to a telephone going off-hook, to serve as an indication that a telephone has gone off-hook and to cause the automatic telecommunications system to relinquish its use of the telephone line, or not to go off-hook if a telephone is in use.
Inventors
- 👤 Joseph A. Damoci
- 👤 Matthew F. Kern
- 👤 Russell J. Welsh
- 👤 John D. Fourdraine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:43
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
196 words
In an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, the improvement comprising means for determining prior to initiating communications with the central location whether a telephone at the remote location is off-hook and for inhibiting communications with the central location if a telephone is off-hook, and further comprising means for determining during the time that communications are established with the central location whether a telephone at the remote location goes off-hook comprises means for generating a test signal and applying the test signal between ring and tip of a telephone line, first and second integrator means having respectively short and relatively long integration time constants for integrating the test signal, comparison means for comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 2
Dependent Claim
196 words
In an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, the improvement comprising means for determining prior to initiating communications with the central location whether a telephone at the remote location is off-hook and for inhibiting communications with the central location if a telephone is off-hook, and further comprising means for determining during the time that communications are established with the central location whether a telephone at the remote location goes off-hook comprises means for generating a test signal and applying the test signal between ring and tip of a telephone line, first and second integrator means having respectively short and relatively long integration time constants for integrating the test signal, comparison means for comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 3
Dependent Claim
187 words
In an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, the improvement comprising means for determining prior to initiating communications with the central location whether a telephone at the remote location is off-hook and for inhibiting communications with the central location if a telephone is off-hook, and further comprising means for determining during the time that communications are establishing with the central location whether a telephone at the remote location goes off-hook comprises first and second integrator means having respectively short and relatively long integration time constants for integrating the data communications signal being transmitted by the modem to the central location, comparison means for comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 4
Dependent Claim
187 words
In an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, the improvement comprising means for determining prior to initiating communications with the central location whether a telephone at the remote location is off-hook and for inhibiting communications with the central location if a telephone is off-hook, and further comprising means for determining during the time that communications are establishing with the central location whether a telephone at the remote location goes off-hook comprises first and second integrator means having respectively short and relatively long integration time constants for integrating the data communications signal being transmitted by the modem to the central location, comparison means for comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 5
Independent Claim
196 words
A method of operating an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, comprising the steps of determining prior to initiating communication with the central location whether a telephone at the remote location is off-hook and inhibiting communications with the central location is a telephone is off-hook, and further comprising the step of determining during the time that communications are established with the central location whether a telephone at the remote location goes off-hook includes generating a test signal and applying the test signal between ring and tip of a telephone line, providing the first and second integrator means having respectively short and relatively long integration time constants for integrating the test signal, comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off hook.
Claim 6
Independent Claim
196 words
A method of operating an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, comprising the steps of determining prior to initiating communication with the central location whether a telephone at the remote location is off-hook and inhibiting communications with the central location is a telephone is off-hook, and further comprising the step of determining during the time that communications are established with the central location whether a telephone at the remote location goes off-hook includes generating a test signal and applying the test signal between ring and tip of a telephone line, providing the first and second integrator means having respectively short and relatively long integration time constants for integrating the test signal, comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off hook.
Claim 7
Independent Claim
188 words
A method of operating an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, comprising the steps of determining prior to initiating communication with the central location whether a telephone at the remote location is off-hook and inhibiting communications with the central location if a telephone is off-hook, and further comprising the step of determining during the time that communications re established with the central location whether a telephone at the remote location goes off-hook includes providing first and second integrator means having respectively short and relatively long integration time constants for integrating the data communications signal being transmitted by the modem to the central location, and comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 8
Independent Claim
188 words
A method of operating an automatic telecommunication system including a central location and at least one remote location and wherein a data reporting system including a modem is situated at the remote location for establishing data communications with the central location over the switched telephone network, comprising the steps of determining prior to initiating communication with the central location whether a telephone at the remote location is off-hook and inhibiting communications with the central location if a telephone is off-hook, and further comprising the step of determining during the time that communications re established with the central location whether a telephone at the remote location goes off-hook includes providing first and second integrator means having respectively short and relatively long integration time constants for integrating the data communications signal being transmitted by the modem to the central location, and comparing the integrated signal outputs of said first and second integrators, whereby a substantial difference between the integrated signal outputs of said first and second integrators is indicative that an additional load has been placed between tip and ring of the telephone line, corresponding to a telephone going off-hook.
Claim 9
Dependent Claim
29 words
Apparatus in accordance with claim 1 or 3, wherein said test signal is a predetermined low frequency signal and different from the frequency of the modem signal in frequency.
References Cited (Backward Citations)
US3564143A
Cited
US3588357A
Cited
US4002837A
Cited
US4059727A
Cited
US4104486A
Cited
US4132864A
Cited
US4321429A
Cited
US4455453A
Cited
US4310724A
Cited
US4306116A
Cited
US4392023A
Cited
US4337378A
Cited
US4394540A
Cited
US4429185A
Cited
US4477698A
Cited
US4486625A
Cited
US4469917A
Cited
US4540854A
Cited
US4521643A
Cited
US4578700A
Cited
US4578536A
Cited
US4660218A
Cited
US4640988A
Cited
US4596021A
Cited
GB2163624A
Cited
US4674117A
Cited
US4833618A
Cited
US4742536A
Cited
US4766548A
Cited
US4811389A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |