US2550585A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone identification circuit
Assignee: AT&T Inc
•
Filing: 1949-04-26
•
Granted: 1951-04-24
•
Expires: 1969-04-26
Abstract
No abstract record available.
Inventors
- 👤 Richard P Murphy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:59
CPC Classifications
H; H04; H04M; H04M15/00; H04M15/08
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2299513A
Cited
US2267950A
Cited
US2270246A
Cited
US2319424A
Cited
US2252766A
Cited
US2344612A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-04-23 | 1954-10-23 | 1955-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-04-23 | 1958-10-23 | 1959-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-04-23 | 1962-10-23 | 1963-04-24 | $7700.00 | Window Closed / Lapsed |