How Did Erna Schneider Hoover Advance Communications?

In 1972, National Inventors Hall of Fame^® Inductee Erna Schneider Hoover, a trailblazing mathematician, professor and inventor, changed how calls were connected when she patented her computerized telephone switching system. Read on to learn more about her invention journey.

Early Curiosity

Hoover was born in Irvington, New Jersey, in 1926. Her mother was a teacher and her father a dentist, and she had two younger siblings. From a young age, Hoover found herself drawn to science. She particularly was inspired by the biography of Marie Curie, whose story helped her believe she could reach any goal she set for herself.

After graduating from high school, Hoover enrolled at Wellesley College, where she decided to study medieval history. She earned her bachelor’s degree in the subject in 1948. She then continued her education at Yale University, where she graduated in 1951 with a doctorate in philosophy and the foundations of mathematics.

Hoover first took a position as a professor at Swarthmore College, where she taught philosophy and logic until 1953, and in 1954, she accepted a research position at Bell Labs, where she would follow a transformative path.

Unstoppable Ingenuity

At the time Hoover joined Bell Labs, the company was planning to replace its hard-wired, mechanical telephone switching system and had begun exploring electronic switch systems (ESS), which could process calls more efficiently as telephone traffic increased. Working toward this goal, Hoover began developing stored program control (SPC) system software to process calls as they took place.

Hoover began sketching her plans for a new telephone switching system in a most unconventional place – she was in a hospital maternity ward after giving birth to her second daughter.

Continuing to work on her idea, both in the hospital and at home, she developed a program that would monitor the frequency of incoming calls and automatically adjust the acceptance rate. This groundbreaking system resulted in more robust service during busy call times and eliminated system overloads.

Describing her work, Hoover said, “I designed the executive program for handling situations when there were too many calls, to keep it operating efficiently without hanging up on itself. Basically, it was designed to keep the machine from throwing up its hands and going berserk.”

In 1957, Hoover entered the Bell Labs internal training program, which now is considered the equivalent of earning a master’s degree in computer science. She then joined a team working on the No. 1 ESS computer – the first large-scale ESS – and she wrote the specifications for this computer and its operating system. This led her to earn a significant promotion, as she became the supervisor of a technical department at Bell Labs.

Tenacious Leadership

A key contribution to the system architecture of the first electronic telephone central office developed by Bell Labs, Hoover’s SPC system achieved an unprecedented level of flexibility and advanced modern communications.

In 1963, the first SPC system went into service for a private business. By 1965, these systems were in service in the public network. Today, all SPC systems are based on Hoover’s innovative designs, and they are used in a wide range of applications, from cellphone services to the internet.

When Hoover patented her computerized telephone switching system in 1972, this was one of the first patents ever granted for software.

In 1978, Hoover was promoted to technical department head at Bell Labs. She managed several groups of programmers developing the U.S. Anti-Ballistic Missile system known as the Safeguard Program, and she worked on software applications with a focus on artificial intelligence and IMS-IBM/Unix-based system communications. Hoover retired in 1987, after 32 years at Bell Labs.

Having joined the New Jersey Board of Higher Education in 1983 and serving as a chairperson of the Trenton State College Board of Trustees, now called the College of New Jersey, Hoover was known to be a “tenacious, energetic leader.” In 2020, she was awarded an honorary degree, Doctor of Humane Letters, for her contributions to higher education in New Jersey.

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