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US2852612A
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US
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Multistation telephone intercommunicating and conference system
Assignee: AT&T Inc
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Filing: 1955-12-21
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Granted: 1958-09-16
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Expires: 1975-12-21
Abstract
No abstract record available.
Inventors
- 👤 Baker Donn
- 👤 Herman T Carter
- 👤 Sylvester A Kelnhofer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:01
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/42; H04M3/56; H04M9/00; H04M9/002; H04M9/005
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1492995A
Cited
US1665466A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-09-15 | 1962-03-17 | 1962-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-09-15 | 1966-03-17 | 1966-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-09-15 | 1970-03-17 | 1970-09-16 | $7700.00 | Window Closed / Lapsed |