US2644039A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit arrangement for conference call installations
Assignee: International Standard Electric Corp
•
Filing: 1950-08-11
•
Granted: 1953-06-30
•
Expires: 1970-08-11
Abstract
No abstract record available.
Inventors
- 👤 Rensch Heinz Robert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:37
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/001
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US2054933A
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US2162370A
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US2162369A
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US2275406A
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US2249456A
Cited
US2449344A
Cited
US2427850A
Cited
US2529912A
Cited
US2567484A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-06-29 | 1956-12-29 | 1957-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-06-29 | 1960-12-29 | 1961-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-06-29 | 1964-12-29 | 1965-06-30 | $7700.00 | Window Closed / Lapsed |