Granted Patent
Utility
US 5,459,781 · App. 08/180,883
Selectively activated dual tone multi-frequency detector
Inventors:
Jeffrey Kaplan, Nicholas Zwick
Patented Case
View Patent ↗
Granted: Oct 17, 1995
Filed: Jan 12, 1994
Inventors
Jeffrey Kaplan
Nicholas Zwick
Assignee (at issue)
Dialogic 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.