Long before smartphones and cell phones, there were telephones. They were all the rage. In 1967, so many people were using telephones that the number of calls was causing major problems for Bell Telephone. The company, founded by Alexander Graham Bell in 1877, provided telephone service to the United States and Canada until it was broken up in 1984 into smaller companies by the U.S. Department of Justice.
Hoover, who had a doctorate in philosophy and mathematics from Yale University, was working at Bell Telephone in the '60s. The company, overwhelmed by the number of calls, wanted to replace its mechanical call switching system with something that was faster and more efficient. The switches routed calls from one telephone to another [source: MIT].
Hoover, who was in the hospital after giving birth to one of her daughters, drew up the plans for the first computerized switching system. The computer monitored the frequency of calls during different times of the day. It stopped Bell Telephone's call system from overloading. Callers got better service during peak call hours [source: Invent.org]. Telephone companies still use that switching system.