US2974281A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective signal recognition system
Assignee: AT&T Inc
•
Filing: 1957-11-01
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Granted: 1961-03-07
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Expires: 1977-11-01
Abstract
No abstract record available.
Inventors
- 👤 Carl B H Feldman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:25
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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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) | 1964-03-06 | 1964-09-05 | 1965-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-03-06 | 1968-09-05 | 1969-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-03-06 | 1972-09-05 | 1973-03-07 | $7700.00 | Window Closed / Lapsed |