Granted Patent
Utility
US 4,720,853 · App. 07/003,643
Ring signal discriminator
Inventor:
Aleksander Szlam
Patented Case
View Patent ↗
Granted: Jan 19, 1988
Filed: Mar 9, 1987
Inventor
Aleksander Szlam
Assignee (at issue)
Melita Electronic 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.