<P> TAT - 1 ( Transatlantic No. 1 ) was the first transatlantic telephone cable system . It was laid between Gallanach Bay , near Oban , Scotland and Clarenville , Newfoundland between 1955 and 1956 by the cable ship Monarch . It was inaugurated on September 25 , 1956 , initially carrying 36 telephone channels . In the first 24 hours of public service there were 588 London -- U.S. calls and 119 from London to Canada . The capacity of the cable was soon increased to 48 channels . Later , an additional three channels were added by use of C Carrier equipment . Time - assignment speech interpolation ( TASI ) was implemented on the TAT - 1 cable in June 1960 and effectively increased the cable 's capacity from 37 ( out of 51 available channels ) to 72 speech circuits . TAT - 1 was finally retired in 1978 . Later coaxial cables , installed through the 1970s , used transistors and had higher bandwidth . The Moscow -- Washington hotline was initially connected through this system . </P>
<P> TAT - 1 ( Transatlantic No. 1 ) was the first transatlantic telephone cable system . It was laid between Gallanach Bay , near Oban , Scotland and Clarenville , Newfoundland between 1955 and 1956 by the cable ship Monarch . It was inaugurated on September 25 , 1956 , initially carrying 36 telephone channels . In the first 24 hours of public service there were 588 London -- U.S. calls and 119 from London to Canada . The capacity of the cable was soon increased to 48 channels . Later , an additional three channels were added by use of C Carrier equipment . Time - assignment speech interpolation ( TASI ) was implemented on the TAT - 1 cable in June 1960 and effectively increased the cable 's capacity from 37 ( out of 51 available channels ) to 72 speech circuits . TAT - 1 was finally retired in 1978 . Later coaxial cables , installed through the 1970s , used transistors and had higher bandwidth . The Moscow -- Washington hotline was initially connected through this system . </P>
when was the first transatlantic telephone cable service opened
when was the first transatlantic telephone cable service opened
September 25 , 1956
September 25 , 1956