US3435150A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Private branch exchange system having data transmission lines and means for preventing application of tones thereto
Assignee: AT&T Inc
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Filing: 1965-12-03
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Granted: 1969-03-25
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Expires: 1985-12-03
Abstract
No abstract record available.
Inventors
- 👤 Erwin H Albrecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:59
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/58; H04Q3/62; H04Q3/625
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) | 1972-03-24 | 1972-09-23 | 1973-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-03-24 | 1976-09-23 | 1977-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-03-24 | 1980-09-23 | 1981-03-25 | $7700.00 | Window Closed / Lapsed |