Granted Patent
Utility
US 5,528,663 · App. 08/508,789
DTMF detection for voice processing equipment
Inventors:
Michael E. Locke, Morteza Hagh-Panah
Patented Case
View Patent ↗
Granted: Jun 18, 1996
Filed: Jul 26, 1995
Inventors
Michael E. Locke
Morteza Hagh-Panah
Assignee (at issue)
Siemens Rolin Communication 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.