US2440239A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-way carrier wave telephone system
Assignee: AT&T Inc
•
Filing: 1945-12-06
•
Granted: 1948-04-27
•
Expires: 1965-12-06
Abstract
No abstract record available.
Inventors
- 👤 Milton L Almquist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:04
CPC Classifications
H; H04; H04M; H04M7/00; H04M7/16
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2383908A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1951-04-27 | 1951-10-27 | 1952-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1955-04-27 | 1955-10-27 | 1956-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1959-04-27 | 1959-10-27 | 1960-04-27 | $7700.00 | Window Closed / Lapsed |