US2572074A
Expired / Lapsed
US
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Voice-frequency signaling system
Assignee: International Standard Electric Corp
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Filing: 1948-07-07
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Granted: 1951-10-23
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Expires: 1968-07-07
Abstract
No abstract record available.
Inventors
- 👤 Terry Victor John
- 👤 Hargreaves Thomas Fred Stanley
- 👤 Gould William Frederick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:16
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45
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) | 1954-10-22 | 1955-04-23 | 1955-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-10-22 | 1959-04-23 | 1959-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-10-22 | 1963-04-23 | 1963-10-23 | $7700.00 | Window Closed / Lapsed |