US2847508A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stage-by-stage all-relay telephone switching system using voice frequency control
Assignee: AT&T Inc
•
Filing: 1954-02-04
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Granted: 1958-08-12
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Expires: 1974-02-04
Abstract
No abstract record available.
Inventors
- 👤 William H T Holden
- 👤 Vroom Edward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:35
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/0008
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2204759A
Cited
US2308778A
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US2277228A
Cited
US2317471A
Cited
US2773934A
Cited
US2580095A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-08-11 | 1962-02-10 | 1962-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-08-11 | 1966-02-10 | 1966-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-08-11 | 1970-02-10 | 1970-08-12 | $7700.00 | Window Closed / Lapsed |