Granted Patent
Utility
US 4,331,843 · App. 06/220,497
Apparatus for controlling and indicating the integrity of the connection of telephone subscribers to a switching system
Inventors:
Lloyd A. Tarr, John Taylor, John Stewart Young
Patented Case
View Patent ↗
Granted: May 25, 1982
Filed: Dec 29, 1980
Inventors
Lloyd A. Tarr
John Taylor
John Stewart Young
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.