He started his career at AT&T in 1924, working as a $25-a-week digger of telephone poles for one of its subsidiaries, the Northwestern Bell Telephone Company in Minnesota. In 1954, he became president of Western Electric, another subsidiary. In 1956, he was elected president of the American Telephone and Telegraph Company, later renamed AT&T. He also served as its chairman from 1961 to 1972. He served as chairman of The Business Council from 1963 to 1964.
President Lyndon B. Johnson appointed him as chairman of presidential commissions, including the Commission on Postal Organization and, in 1967, to a special mediation board in a railroad dispute.V President Richard M. Nixon appointed him as a governor of the United States Postal Service and, from 1972 to 1974, as its chairman. He was on the cover of Time Magazine on May 29, 1964. He received the Presidential Medal of Freedom in 1964 and the John Fritz Medal in 1965.
He served on the boards of directors of Chase Manhattan Bank and General Foods. He also served as chairman of the board of International Paper from 1969 to 1971, and chairman of its executive committee from 1971 to 1972.