Transatlantic telephone cable
A transatlantic telephone cable is a submarine communications cable that carries telephone traffic under the Atlantic Ocean between North America and Europe.While the first transatlantic telegraph cable had been laid in 1858 (Cyrus Field), it had only operated for a month. Attempts in 1865 and 1866 were more successful but although a telephone cable was discussed from the 1920s it needed a number of technological advances that did not arrive until the 1940s to be practical. Until TAT-1 the transatlantic telephone service was radio-based, started in 1927 it cost £9 for three minutes and took around 2000 calls a year.
TAT-1 (Transatlantic No. 1) was the first submarine transatlantic telephone cable system. It was laid between Gallanach Bay, near Oban, Scotland and Clarenville, Newfoundland between 1955 and 1956. It was inaugurated on September 25 1956, initially carrying 36 telephone channels.
Opened on September 25 1956 in the first 24 hours of public service there were 588 London-US calls and 119 from London to Canada. The capacity of the cable was soon increased to 48 channels. TAT-1 was finally retired in 1978.
There have been a succession of newer transatlantic cable systems. All of the recent systems have used fiber optic transmission, and a self-healing ring topology.
| Cable Name | Date(s) | Initial No. of channels | Final No. of channels | One End | Other End |
| TAT-1 | 1956-1978 | 36 | 48 | Scotland | Newfoundland |
| TAT-2 | 1959-1982 | 48 | 72 | France | Newfoundland |
| TAT-3 | 1963-1986 | 138 | 276 | England | New Jersey |
| TAT-4 | 1965-1987 | 138 | 345 | France | New Jersey |
| TAT-5 | 1970-1993 | 845 | 2112 | Rhode Island | Spain |
| TAT-6 | 1976-1994 | 4,000 | 10,000 | Rhode Island | France |
| TAT-7 | 1978-1994 | 4,000 | 10,500 | New Jersey | England |
| TAT-8* | 1988 | 40,000 | - | USA | France |
| TAT-9 | 1992 | 80,000 | - | USA | Spain |
| TAT-10 | 1992 | 2 x 565Mb/s | - | USA | Germany |
| TAT-11 | 1993 | 2 x 565Mb/s | - | USA | France |
| TAT-12/13 | 1996 | 2 x 5Gb/s | - | ||
| TAT-14 | 2000 | 16 x 10Gb/s | - | USA | England |
| CANTAT-1 | 1961-1986 | 80 | - | Newfoundland | Scotland |
| CANTAT-2 | 1974-1992 | 1,840 | - | Nova Scotia | England |
| CANTAT-3 | 1994 | 2 x 2.5Gb/s | Canada | Europe | |
| PTAT-1 | 1989 | 3 x 140Mb/s? | US-Bermuda | Ireland-UK |
* first fibre optic cable.
TAT are almost all north Atlantic cables, there are a number of non-TAT cables further south - SAT-2, ATLANTIS-2, COLUMBUS III etc.
All TAT cables are joint ventures between AT&T and some European telco, e.g. British Telecom. CANTAT are Canadian Transatlantic Telephone cables. A private competitor during the 1990s was Global Crossing.
