Granted Patent
Utility
US 6,700,973 · App. 09/395,778
System for transmitting DTMF signal and communication equipment thereof
Inventors:
Shinya Suzuki, Kimitoshi Takeuchi, Toru Yoshihara, Makoto Oohashi
Patented Case
View Patent ↗
Granted: Mar 2, 2004
Filed: Sep 14, 1999
Inventors
Shinya Suzuki
Kimitoshi Takeuchi
Toru Yoshihara
Makoto Oohashi
Assignee (at issue)
Hitachi Telecom Technologies, Ltd
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.