Wikipedia
TAT-1
TAT-1 (Transatlantic No. 1) was the first submarine transatlantic telephone cable system. It was laid between Oban, Scotland and Clarenville, Newfoundland. Two cables were laid between 1955 and 1956 with one cable for each direction. It was inaugurated on September 25, 1956. The cable was able to carry 35 simultaneous telephone calls. A 36th channel was used to carry up to 22 telegraph lines.