Granted Patent
Utility
US 4,398,147 · App. 06/254,563
Methods of testing multifrequency dialing signals
Inventor:
Timothy A. Shankland
Patented Case
View Patent ↗
Granted: Aug 9, 1983
Filed: Apr 15, 1981
Inventor
Timothy A. Shankland
Assignee (at issue)
Western Electric Company, Inc.
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.