Granted Patent
Utility
US 4,490,582 · App. 06/467,783
Speakerphone control circuit
Inventor:
Verne E. Munson
Patented Case
View Patent ↗
Granted: Dec 25, 1984
Filed: Feb 18, 1983
Inventor
Verne E. Munson
Assignee (at issue)
AT&T Information Systems 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.