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.

The first transatlantic telegraph cable had been laid in 1858 (see Cyrus West Field). It only operated for a month, but was replaced with a successful connection in 1866. A radio-based transatlantic telephone service was started in 1927, charging £9 (about $45 USD, or roughly $550 in 2010 dollars) for three minutes and handling around 300,000 calls a year. Although a telephone cable was discussed at that time, it was not practical until a number of technological advances arrived in the 1940s.

The developments that made TAT-1 possible were coaxial cable, polyethylene insulation (replacing gutta-percha), very reliable vacuum tubes for the submerged repeaters and a general improvement in carrier equipment. Transistors were not used, being a recent invention of unknown longevity.

The agreement to make the connection was announced by the Postmaster General on December 1, 1953. The project was a joint one between the General Post Office of the UK, the American Telephone and Telegraph company, and the Canadian Overseas Telecommunications Corporation. The share split in the scheme was 40% British, 50% American, and 10% Canadian. The total cost was about £120 million.

There were to be two main cables, one for each direction of transmission. Each cable was produced and laid in three sections, two shallow-water armored sections, and one continuous central section 1,500 nautical miles (2,800 km) long. The electronic repeaters were designed by the Bell Telephone Laboratories of the United States and they were flexible and were inserted into the cable at 37-nautical-mile (69 km) intervals – a total of 51 repeaters in the central section. The armored cables were manufactured southeast of London, at a factory in Erith, Kent, owned by Submarine Cables Ltd. (owned jointly by Siemens Brothers & Co, Ltd, and The Telegraph Construction & Maintenance Company, Ltd).

...
Wikipedia