Patent US2640872A successfully refreshed from Google Patents.
US2640872A
Expired / Lapsed
US
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Telecommunication exchange system
Assignee: International Standard Electric Corp
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Filing: 1949-04-29
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Granted: 1953-06-02
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Expires: 1969-04-29
Abstract
No abstract record available.
Inventors
- 👤 Hartley George Clifford
- 👤 Weir Donald Adams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:17
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/0016; H04L; H04L12/00
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) | 1956-06-01 | 1956-12-01 | 1957-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-06-01 | 1960-12-01 | 1961-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-06-01 | 1964-12-01 | 1965-06-02 | $7700.00 | Window Closed / Lapsed |