US2591580A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Special trunk circuits for transmitting tones to calling subscribers
Assignee: CRIMSON ENGINEERED SOLUTIONS LLC
•
Filing: 1948-10-29
•
Granted: 1952-04-01
•
Expires: 1968-10-29
Abstract
No abstract record available.
Inventors
- 👤 Michal Joseph
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:39
CPC Classifications
H; H04; H04Q; H04Q3/00
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1678503A
Cited
US1437357A
Cited
US1628358A
Cited
US2293620A
Cited
US2332878A
Cited
US2355908A
Cited
US2508646A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1955-04-01 | 1955-10-01 | 1956-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1959-04-01 | 1959-10-01 | 1960-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1963-04-01 | 1963-10-01 | 1964-04-01 | $7700.00 | Window Closed / Lapsed |