US2987575A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two way telephone handset amplifying system
Assignee: Individual
•
Filing: 1955-11-10
•
Granted: 1961-06-06
•
Expires: 1975-11-10
Abstract
No abstract record available.
Inventors
- 👤 Norman L Chalfin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:54
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/60; H04M1/62; H04M1/02; H04M1/21; H04M1/215; H04M1/2155
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) | 1964-06-05 | 1964-12-05 | 1965-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-06-05 | 1968-12-05 | 1969-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-06-05 | 1972-12-05 | 1973-06-06 | $7700.00 | Window Closed / Lapsed |