Granted Patent
Utility
US 4,747,124 · App. 06/731,171
PBX telephone call control system
Inventor:
David Ladd
Patented Case
View Patent ↗
Granted: May 24, 1988
Filed: May 6, 1985
Inventor
David Ladd
Assignee (at issue)
OPCOM 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.