Patent US2810016A successfully refreshed from Google Patents.
US2810016A
Expired / Lapsed
US
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Key telephone set holding circuit
Assignee: AT&T Inc
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Filing: 1955-12-27
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Granted: 1957-10-15
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Expires: 1975-12-27
Abstract
No abstract record available.
Inventors
- 👤 Gale L Knittle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:24
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002; H04M9/005; H04M9/006; H04M1/00; H04M1/26; H04M1/52
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) | 1960-10-14 | 1961-04-15 | 1961-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-10-14 | 1965-04-15 | 1965-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-10-14 | 1969-04-15 | 1969-10-15 | $7700.00 | Window Closed / Lapsed |