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US2533342A
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Tandem switching system
Assignee: AT&T Inc
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Filing: 1947-10-09
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Granted: 1950-12-12
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Expires: 1967-10-09
Abstract
No abstract record available.
Inventors
- 👤 Avery Robert Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:05
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/0004
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) | 1953-12-11 | 1954-06-12 | 1954-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-12-11 | 1958-06-12 | 1958-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-12-11 | 1962-06-12 | 1962-12-12 | $7700.00 | Window Closed / Lapsed |