Granted Patent
Utility
US 4,394,544 · App. 06/319,563
Line circuit for multiple line telephone
Inventor:
Daniel De Leon
Patented Case
View Patent ↗
Granted: Jul 19, 1983
Filed: Nov 9, 1981
Inventor
Daniel De Leon
Assignee (at issue)
GTE Automatic Electric Labs 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.