Granted Patent
Utility
US 4,706,278 · App. 06/813,188
Interface circuit for transmitting keycodes to a CENTREX
Inventor:
James B. Black
Patented Case
View Patent ↗
Granted: Nov 10, 1987
Filed: Dec 24, 1985
Inventor
James B. Black
Assignee (at issue)
GTE Communication Systems 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.