CA2428619A1 - Parallel off-hook detection for both line-available and phone pick-up detection - Google Patents
Parallel off-hook detection for both line-available and phone pick-up detection Download PDFInfo
- Publication number
- CA2428619A1 CA2428619A1 CA002428619A CA2428619A CA2428619A1 CA 2428619 A1 CA2428619 A1 CA 2428619A1 CA 002428619 A CA002428619 A CA 002428619A CA 2428619 A CA2428619 A CA 2428619A CA 2428619 A1 CA2428619 A1 CA 2428619A1
- Authority
- CA
- Canada
- Prior art keywords
- line
- telephone
- hook
- steady
- seizure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001514 detection method Methods 0.000 title 2
- 239000003990 capacitor Substances 0.000 abstract 2
Landscapes
- Telephonic Communication Services (AREA)
- Facsimiles In General (AREA)
- Prepayment Telephone Systems (AREA)
Abstract
A secondary communications device, such as a modem, a facsimile machine, an automatic meter reader or an answering machine, shares a telephone line with a subscriber's telephone and must grant the telephone primary access to the line. The present invention prevents the secondary device from seizing the line when the telephone is already off-hook and will terminate a line seizure by the secondary device if the subscriber picks up the telephone handset during use of the line by the secondary device. An average interval for charging a capacitor to a threshold voltage in response to an on-hook voltage appearing across the telephone line is determined. When the secondary communications device is ready to use the line, circuitry measures an interval for charging the capacitor in response to the current voltage appearing across the telephone line. The secondary communication device seizes the line only if the measured interval does not exceed the average interval by more than a predetermined amount. After seizure by the secondary communication device, a steady-state condition is brought about between the secondary device, the line steady-state impedance, and the central office voltage source. If the line impedance drops from the steady-state value, the circuitry assumes that the subscriber has taken the telephone off-hook and terminates the line seizure by the secondary device.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/102,325 | 1993-08-05 | ||
US08/102,325 US5422939A (en) | 1993-08-05 | 1993-08-05 | Parallel off-hook detection for both line-available and phone pick-up detection |
CA002119972A CA2119972C (en) | 1993-08-05 | 1994-03-25 | Parallel off-hook detection for both line-available and phone pick-up detection |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002119972A Division CA2119972C (en) | 1993-08-05 | 1994-03-25 | Parallel off-hook detection for both line-available and phone pick-up detection |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2428619A1 true CA2428619A1 (en) | 1995-02-06 |
CA2428619C CA2428619C (en) | 2006-06-27 |
Family
ID=25677144
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002428619A Expired - Fee Related CA2428619C (en) | 1993-08-05 | 1994-03-25 | Parallel off-hook detection for both line-available and phone pick-up detection |
Country Status (1)
Country | Link |
---|---|
CA (1) | CA2428619C (en) |
-
1994
- 1994-03-25 CA CA002428619A patent/CA2428619C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
CA2428619C (en) | 2006-06-27 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request | ||
MKLA | Lapsed |