Granted Patent
Utility
US 6,400,709 · App. 09/204,607
DTMF detection in internet telephony
Inventor:
Khalid Yousseff
Patented Case
View Patent ↗
Granted: Jun 4, 2002
Filed: Dec 2, 1998
Inventor
Khalid Yousseff
Assignee (at issue)
Intel Corporation
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.