US2620402A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone substation circuit with automatic compensation for length of line
Assignee: AT&T Inc
•
Filing: 1947-12-22
•
Granted: 1952-12-02
•
Expires: 1967-12-22
Abstract
No abstract record available.
Inventors
- 👤 Botsford Nelson
- 👤 Jr Albert P Boysen
- 👤 Andrew J Aikens
- 👤 Jr Walter D Goodale
- 👤 Alfred H Inglis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:41
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/738; H04M1/76; H04M1/58
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1399775A
Cited
US1442427A
Cited
US1464118A
Cited
US1555037A
Cited
US1518440A
Cited
US1641233A
Cited
US1993780A
Cited
US2164033A
Cited
US2202386A
Cited
US2288049A
Cited
US2287998A
Cited
US2260296A
Cited
US2360233A
Cited
US2431306A
Cited
US2387269A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1955-12-02 | 1956-06-02 | 1956-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1959-12-02 | 1960-06-02 | 1960-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1963-12-02 | 1964-06-02 | 1964-12-02 | $7700.00 | Window Closed / Lapsed |