Granted Patent
Utility
US 5,940,475 · App. 08/865,699
Telephone system integrated text based communication apparatus and system to enhance access for TDD and/or TTY devices
Inventor:
Frederick W. Hansen
Patented Case
View Patent ↗
Granted: Aug 17, 1999
Filed: May 30, 1997
Inventor
Frederick W. Hansen
Assignee (at issue)
Nortel Networks Limited
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.