In 1950, the Mayo Clinic switchboards were experiencing 6,500,000 calls annually. For an average work day, this resulted in approximately 21,000 calls; about 7,500 outgoing, 6,000 in-coming, and 7,500 inter-Clinic calls.
During this time, the Mayo Clinic telephone system had about 1,100 telephones and 700 loudspeakers, which is equivalent to that of a city with a population of more than 6,000.
The heart of the telephone system was a five-position board (capable of expansion), with 10 strictly incoming and several two-way lines. There were 10 direct lines to Saint Marys, three each to the Worrall, Kahler, and Colonial Hospitals.