President Rutherford B. Hayes was the first president to use a phone. His phone number was simply 1.
In 1879, the first telephone was installed in the White House. At first it was hardly used, because there weren't many other phones in Washington to call. Hayes had the White House's first telephone installed in the mansion's telegraph room. The White House phone number was '1'. Additional Hayes fact: He gained the Presidency by a margin of only one electoral vote.