Granted Patent
Utility
US 4,647,723 · App. 06/732,122
Circuit for detection of off-hook condition of extension telephones
Inventor:
Kenny R. Voorhies
Patented Case
View Patent ↗
Granted: Mar 3, 1987
Filed: May 9, 1985
Inventor
Kenny R. Voorhies
Assignee (at issue)
GTE Communication Systems Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.