Granted Patent
Utility
US 5,995,604 · App. 08/880,173
Method of preventing fraudulent toll calls by key system users
Inventors:
Ken Chan, Christoph Koch, Shirley-Ann Ivan-Milaknis
Patented Case
View Patent ↗
Granted: Nov 30, 1999
Filed: Jun 20, 1997
Inventors
Ken Chan
Christoph Koch
Shirley-Ann Ivan-Milaknis
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.