US3718781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integrity check equipment for automatic trunk substitution
Assignee: AT&T Inc
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Filing: 1971-12-30
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Granted: 1973-02-27
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Expires: 1991-12-30
Abstract
Abstract IS NOT RECEIVED TO INDICATE A VALID SUBSTITUTION. CIRCUITRY IS ALSO DISCLOSED FOR AUTOMATICALLY INDICATING A TROUBLE AS A RESULT OF THE AUTOMATIC TEST PROCEDURES. THIS SPECIFICATION DISCLOSES EQUIPMENT FOR CHECKING THE INTEGRITY OF TRUNK SUBSTITUTIONS ACCOMPLISHED BY CIRCUITRY WHICH AUTOMATICALLY TESTS TRUNKS FOR DEFECTS THAT INPAIR COMMUNICATIONS AND THEN AUTOMATICALLY SUBSTITUTES A SPARE TRUNK FOR A DEFECTIVE TRUNK. THE EQUIPMENT INCLUDES CHECK CIRCUITS FOR TRUNK SUBSTITUTION ACKNOWLEDGMENT SIGNALS, CODED MULTIDIGIT TRUNK SUBSTITUTION CONTROL SIGNALS AND FURTHER INCLUDES AUTOMATIC TEST CIRCUITS FOR REATTEMPTING TRUNK SUBSTITUTION WHEN AN ACKNOWLEDGEMENT SIGNAL
Inventors
- 👤 R Angner
- 👤 P Daniele
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:59
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/74
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |