Granted Patent
Utility
US 4,488,291 · App. 06/445,629
Circuit arrangement for setting up a conference call
Inventors:
Joachim Eschmann, J/u/ rgen Zanzig
Patented Case
View Patent ↗
Granted: Dec 11, 1984
Filed: Nov 30, 1982
Inventors
Joachim Eschmann
J/u/ rgen Zanzig
Assignee (at issue)
International Standard Electric 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.