Granted Patent
Utility
US 5,896,571 · App. 08/670,788
Switch control method for dual tone multi-frequency service of MSC
Inventors:
Sook Yang KANG, Dae-sik Kim
Patented Case
View Patent ↗
Granted: Apr 20, 1999
Filed: Jun 24, 1996
Inventors
Sook Yang KANG
Dae-sik Kim
Assignee (at issue)
ELECTRONICS AND TELECOMMUNICATIONS RESEARCH INSTITUTE
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.