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US2909609A
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Connecting device for sending tone frequency alternating current signals over a two-conductor line
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1955-10-05
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Granted: 1959-10-20
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Expires: 1975-10-05
Abstract
No abstract record available.
Inventors
- 👤 Svala Carl Gunnar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:39
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/26; H04M1/30; H04M1/50; H04Q; H04Q3/00; H04Q3/42
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) | 1962-10-19 | 1963-04-20 | 1963-10-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1966-10-19 | 1967-04-20 | 1967-10-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1970-10-19 | 1971-04-20 | 1971-10-20 | $7700.00 | Window Closed / Lapsed |