Patent US3621691A successfully refreshed from Google Patents.
Patent US1917879A successfully refreshed from Google Patents.
US1917879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone system
Assignee: AT&T Inc
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Filing: 1931-08-22
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Granted: 1933-07-11
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Expires: 1951-08-22
Abstract
No abstract record available.
Inventors
- 👤 John B Draper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:41
CPC Classifications
H; H04; H04M; H04M5/00; H04M5/04; H04M5/06
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1936-07-10 | 1937-01-09 | 1937-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1940-07-10 | 1941-01-09 | 1941-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1944-07-10 | 1945-01-09 | 1945-07-11 | $7700.00 | Window Closed / Lapsed |