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US2421169A
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Automatic telephone system directed with the aid of revertive audio-frequency signals
Assignee: Automatic Electric Laboratories Inc
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Filing: 1944-05-27
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Granted: 1947-05-27
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Expires: 1964-05-27
Abstract
No abstract record available.
Inventors
- 👤 Taylor Reginald
- 👤 Baker George Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:34
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/58; H04Q3/62; H04Q3/625; C; C03; C03B; C03B5/00; C03B5/12
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1950-05-26 | 1950-11-25 | 1951-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1954-05-26 | 1954-11-25 | 1955-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1958-05-26 | 1958-11-25 | 1959-05-27 | $7700.00 | Window Closed / Lapsed |