Cortelco can trace its roots back to the Kellogg Switchboard and Supply Company. In 1870, Milo G. Kellogg moved to Chicago and began working as an engineer for telecommunications equipment maker Gray & Barton, which soon became Western Electric.
In the late 1880s, he left Western Electric and began designing telecommunications devices on his own. By the time he had founded Kellogg Switchboard & Supply Co. in 1897, Kellogg had registered well over 100 patents, some of which would revolutionize the telecommunications industry.
Kellogg Switchboard & Supply soon threatened the dominance of AT&T by selling its superior “divided-multiple” switchboards to the newly created independent telephone companies around the country.
After Kellogg fell seriously ill in 1901, AT&T secretly purchased his stock in Kellogg Switchboard from Mr. Kellogg's temporary trustee. The Illinois Supreme Court canceled the surreptitious acquisition in 1909, and Milo Kellogg regained control of his company after eight years of phantom ownership by AT&T.
After Mr. Kellogg's death that same year, Kellogg Switchboard continued to grow, eventually supplying equipment to AT&T's Western Electric.
The company's entrance into the dial telephone business in 1939 buoyed sales, which hit $10 million by the mid-1940s. Kellogg became a division of the International Telephone and Telegraph (ITT) in 1952.
During the 1960’s and 70’s the business name and its affiliation with various other ITT divisions underwent various changes, but the changes had very little impact on the day-to-day operations of the ITT telecommunications
factory in Corinth, Mississippi.
During the 80s the Corinth facility was part of a joint venture between ITT and CGE, transferring the majority of
ownership to the newly-formed Alcatel, the world’s largest telecommunications manufacturer, based in France. Shortly after this merger, the American operation was named Cortelco – an acronym for Corinth Telecommunications
Corporation. In 1990, Alcatel sold Cortelco to former ITT executive, David S. Lee.