Awarded U.S. Patent No. 3,623,007 for a stored-program telephone switching method, among the first software patents ever issued.
On November 30, 1971, the United States Patent and Trademark Office issued U.S. Patent No. 3,623,007, titled "Feedback Control Monitor for Stored Program Data Processing System," to Erna Schneider Hoover. The patent covered a method for a computerized telephone switching system that dynamically monitored incoming call traffic and adjusted the processing priority of tasks in real time to prevent the system from becoming overloaded during peak calling periods, such as holidays or emergencies.
What made this invention especially remarkable was that it existed almost entirely in software—a stored program running on a computer—rather than in physical, mechanical switching hardware, which had been the norm in telephony up to that point. Because software patents were exceedingly rare in this era, and the legal framework for patenting logical/algorithmic processes was still being established, this patent is widely cited by historians of technology and by the National Inventors Hall of Fame as one of the very first, if not the first, software patents ever granted in the United States.
Hoover conceived the core idea while recovering from childbirth, reportedly working out the logical structure of the priority scheme with pencil and paper rather than a computer terminal. Her invention allowed the No. 1 Electronic Switching System (1ESS) to handle far greater call volumes without crashing, fundamentally improving the reliability of the American telephone network and paving the way for modern computerized communication infrastructure.