IP Library › Granted Patent US 4,309,574
Granted Patent Utility
US 4,309,574 · App. 06/140,525

Electronic tone ringer

Inventors: John D. Sublette, William Stobbs
Patented Case View Patent ↗
Granted: Jan 5, 1982 Filed: Apr 15, 1980
Inventors
John D. Sublette
William Stobbs
Assignee (at issue)
GTE Automatic Electric Labs 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.

Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 4,309,574
App. No.
06/140,525
Filed
1980-04-15
Granted
1982-01-05
Kind
A