US2697749A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multifrequency telephone switching system
Assignee: AT&T Inc
•
Filing: 1951-06-20
•
Granted: 1954-12-21
•
Expires: 1971-06-20
Abstract
No abstract record available.
Inventors
- 👤 Armand L Jeanne
- 👤 Arthur C Keller
- 👤 Samuel D White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:47
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/26; H04M1/27; H04M1/272; H04Q; H04Q3/00; H04Q3/0004
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2164335A
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US2244500A
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US2317191A
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US2300622A
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US2346305A
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US2317471A
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US2354668A
Cited
US2554201A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-12-20 | 1958-06-21 | 1958-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-12-20 | 1962-06-21 | 1962-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-12-20 | 1966-06-21 | 1966-12-21 | $7700.00 | Window Closed / Lapsed |