Granted Patent
Utility
US 4,887,288 · App. 07/290,772
Self calibration arrangement for a voice switched speakerphone
Inventor:
Richard Henry Erving
Patented Case
View Patent ↗
Granted: Dec 12, 1989
Filed: Dec 28, 1988
Inventor
Richard Henry Erving
Assignees (at issue)
American Telephone and Telegraph, Co.
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.