The earliest attempt at transatlantic telephony was in 1915 when the American Telephone and Telegraph Company (later known as AT&T) managed to transmit one-way voice signal between the Naval Wireless Station in Arlington, Virginia and the Eiffel Tower in Paris. The limits of available technology and then the First World War brought an end to the experiments. Eight years later AT&T again demonstrated the feasibility of telephone calls between Europe and the United States by sending a speech signal from New York to New Southgate in London.

At that time the General Post Office (GPO) managed the British telephone system and its head, the Postmaster-General, was so impressed with the demonstration that he decided to cooperate with AT&T and the Western Electric Company to create a commercial transatlantic telephone service using radio signals. The GPO built a 200 kilowatt transmitter at the Post Office Station at Rugby and experiments began to improve transmission to such a point that it was commercially viable. Furthermore the telephone network infrastructure in Britain and the United States required substantial development.

In February 1926, the engineers achieved two-way voice communication between the two radio stations and a month later journalists gathered at the trunk exchanges in London and New York to take part in a demonstration of two-way voice communication. Finally, on 7th January 1927, the service opened with a call between Sir Evelyn Murray, the Secretary of the GPO and Walter S. Gifford, the president of AT&T, followed by calls between those subscribers who had booked calls for that day.