Granted Patent
Utility
US 4,394,543 · App. 06/270,507
Telephone line holding circuit
Inventors:
Francis P. Keiper, Jr., John N. Kerns
Patented Case
View Patent ↗
Granted: Jul 19, 1983
Filed: Jun 4, 1981
Inventors
Francis P. Keiper, Jr.
John N. Kerns
Assignee (at issue)
Lear Siegler, 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.