Bell System engineers achieved the first voice transmission across the Atlantic, connecting Virginia and Paris briefly in 1915. A year later, they held the first two-way conversation with a ship at sea, and in 1926, the first two-way conversation across the Atlantic. On January 7, 1927, commercial telephone service (using radio) began between New York and London. Over the next several years, service spread throughout North America and Europe. In 1929, the S.S. Leviathan became the first ocean liner to offer radio telephone service to its passengers and crew. Pacific service began to Hawaii in 1931 and Tokyo in 1934. AT&T celebrated international service in 1935 with the first round-the-world telephone call. The two speakers, AT&T President W.S. Gifford and Vice President T. Miller, were in rooms in the same building, but their voices traveled on a circuit around the globe.

Transoceanic phone service was eventually handled by submarine cables and communications satellites