IP Library › Granted Patent US 4,939,775
Granted Patent Utility
US 4,939,775 · App. 07/283,776

Telephone ringing detector

Inventors: Kenneth Houck, Dewayne A. Spires
Patented Case View Patent ↗
Granted: Jul 3, 1990 Filed: Dec 13, 1988
Inventors
Kenneth Houck
Dewayne A. Spires
Assignee (at issue)
AT&T Bell Laboratories

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Quick Facts
Patent No.
US 4,939,775
App. No.
07/283,776
Filed
1988-12-13
Granted
1990-07-03
Kind
A