First Transatlantic Telephone Cable Begins Operation

The first transatlantic cable, designed to transmit telephone traffic between the United States and Europe, introduced a new era of instantaneous long-distance communications.

Summary of Event

The history of submarine cable design and development is largely a chronicle of repeated frustration and failure. From the time of the first telegraph communication, scientists had attempted to lay cable along the bottoms of waterways in order to connect distant points in as direct a route as possible at minimal cost for right-of-way access. Even before the first lines were constructed on land, telegraph inventor Samuel F. B. Morse had strung a telegraph cable across New York Harbor. Transatlantic telephone cable
Telecommunications;transatlantic cables
[kw]First Transatlantic Telephone Cable Begins Operation (Sept. 25, 1956)
[kw]Transatlantic Telephone Cable Begins Operation, First (Sept. 25, 1956)
[kw]Telephone Cable Begins Operation, First Transatlantic (Sept. 25, 1956)
Transatlantic telephone cable
Telecommunications;transatlantic cables
[g]Atlantic;Sept. 25, 1956: First Transatlantic Telephone Cable Begins Operation[05250]
[g]Europe;Sept. 25, 1956: First Transatlantic Telephone Cable Begins Operation[05250]
[g]United States;Sept. 25, 1956: First Transatlantic Telephone Cable Begins Operation[05250]
[c]Communications and media;Sept. 25, 1956: First Transatlantic Telephone Cable Begins Operation[05250]
[c]Science and technology;Sept. 25, 1956: First Transatlantic Telephone Cable Begins Operation[05250]
Morse, Samuel F. B.
Field, Cyrus West

In 1852, American financier Cyrus West Field organized a company to lay the first telegraph cable from the American continent to Europe. On August 5, 1858, the first cable was in place, and U.S. president James Buchanan communicated with Queen Victoria to inaugurate the first transoceanic electronic communication link. Unfortunately, the euphoria was short-lived. The cable failed a month later, when its insulation was damaged by high-voltage transmission. In 1865, another company tried and failed to lay a new cable. Not until 1869 was the first truly successful effort completed and the first reliable transatlantic cable in place.

The time interval from the invention of the telegraph to the first reliable transoceanic telegraph cable transmissions was relatively short compared to the time it took to deploy a transoceanic telephone cable. The first transatlantic telephone cable was put into service on September 25, 1956, approximately one hundred years after the first telegraph cable. The physical character of telephony Telecommunications;telephony requires much more of cable than does the relatively simple transmission mode used in telegraphy. Voice communication requires that a broad range of vocal characteristics be transmitted successfully over wire, requiring that cable be designed to achieve a high degree of frequency response. As in land-line transmission, submarine cable must carry signals over long distances without significantly distorting them, a challenge whose solution proved elusive to researchers for almost three-quarters of a century.

In fairness, it must be pointed out that early interest in radiotelephony diverted the attention of researchers away from cable for much of the first half of the twentieth century. It was not until after World War II that research on submarine cable design began in earnest. Radiotelephony proved somewhat unreliable for transoceanic communication, as shortwave broadcasts were highly susceptible to interference and noise caused by changes in weather patterns.

A key scientific discovery in the late 1940’s, that of the transistor Transistors;telephony , made the problem of telephone circuit amplification appear solvable. Just as amplifiers, or repeaters, were needed in long-distance land-line transmission to maintain signal strength and quality, so were they necessary in submarine cable for the same reasons. In land lines, however, maintenance of amplifiers was a much simpler task than in submarine cable. Early telephone repeaters were designed to incorporate vacuum tubes, devices used in early broadcasting to amplify and transmit radio waves. While research into their use in submarine cable actually occurred during the 1920’s, the effort was regarded as futile even then.

Transistors held great promise in that they were compact, inexpensive, stable, long-lived, and energy-efficient. The first few years following their discovery, however, proved frustrating to telephone engineers, who were unable to incorporate them successfully in facility designs. Eventually, refinements in the transistor concept led to the breakthrough that resulted in their ultimately successful application in submarine cable design.

Submarine cable had to be designed to withstand the unusual, often hostile environments found at the bottom of the ocean. Pressure, moisture, and cold were formidable opponents, and a variety of cable sheathing and insulating materials used in experiments that simulated such conditions had proved unreliable over the long haul. In addition, over the years, various materials had been used that varied in terms of their elasticity and their ability to withstand heat or cold without cracking or otherwise disintegrating. Following World War II, polyethylene emerged as a primary material for encapsulating wire because of its nonpolarity and relative lack of impurities. After much experimentation, a formula of polyethylene and 5 percent Butyl rubber was used in the manufacture of the SB submarine cable system, the design that would be used ultimately in the construction of the first transatlantic telephone cable.

It was important to submarine cable designers that the transatlantic cable have multicircuit capacity. The first cable included sixty-four voice channels, each of which could be used simultaneously with the others. Each channel was able to transmit a high-quality voice conversation in two directions simultaneously. This represented a significant advantage over radiotelephony, which required the use of two frequencies to accomplish the same task. The cable also had the advantage of a relative lack of interference by atmospheric or human-made electromagnetic conditions.

The 1956 cable deployment and operation was a success. The cable sheathing and insulation proved reliable, and the quality of the circuits was acceptable. Soon, a new system called SD was deployed. It carried 128 two-way circuits and utilized an improved polyethylene resin formula for improved quality and uniformity. Over the next decade, additional cables were laid, each an improvement over the last. By the early 1970’s, yet another system, SG, was put into service with forty-two hundred circuits.

Undersea telephone cable technology was challenged by another emergent technology almost from the time it was first deployed. By 1962, merely six years after the first submarine telephone cable was put into operation, American Telephone and Telegraph American Telephone and Telegraph (AT&T) began to supplement underwater cable with satellite transmission of telephone conversations. The company launched Telstar 1 Telstar 1
Satellites, artificial;telecommunications
Telecommunications;satellites , a satellite that received signals from ground stations, amplified them, then relayed them back to down links around the globe. Telstar contained the equivalent of six hundred voice circuits. Over the years, many more satellites were launched by a number of governmental, military, and commercial interests, expanding the number of satellite voice circuits into the hundreds of thousands. As capacity increased, the cost of using satellites for international voice communication decreased substantially, and the transatlantic telephone cables, although they were still kept in service, became secondary transmission facilities.


Submarine cables were not new in 1956. In fact, the first transoceanic cable had been deployed a century earlier to carry telegraph signals between the United States and continental Europe. The first submarine cable was only a first step in the evolution of underwater transmission facilities. The quality of signals transmitted over it was poor, and signal strength was so weak that it could communicate only a few words per minute. After the invention of the telephone two decades later, attempts to use telegraph cables to transmit telephone conversations were unsuccessful. The distance was too great for the relatively unsophisticated amplification techniques available, and the nature of the steel conductor at the core of the cable made it unacceptable for voice traffic because it was technically incapable of achieving the range of frequency response necessary for voice transmission.

Another factor that influenced the evolution of submarine cable technology was the political situation in Europe during the first half of the twentieth century. Two world wars that polarized much of the European community disrupted the economic and political landscape on that continent, and laying a transatlantic telephone cable during that time would have been a risky proposition at best, an enterprise fraught with uncertainty. In a real sense, the laying of a transatlantic telephone cable was a technical achievement that would have to wait until the mid-1950’s, after the telecommunications infrastructure of that war-torn continent had been rebuilt and the Allied economies stabilized. Also, it was necessary for operators of the U.S. telecommunications network to demobilize and to adjust to the newly emerging opportunities in Europe.

The first transatlantic telephone cable was a significant achievement in telephony, but it also represented the first step in the establishment of a truly global, instantaneous electronic voice communication network. Its deployment two years before Sputnik, the first human-made satellite to circle the earth, meant that virtually every home with a telephone was connected to the transoceanic network. It was a significant achievement in the design of long-distance conductors, amplifiers, and submarine cable insulation and sheathing. For the first time, the reliability of submarine telephone circuitry had been demonstrated successfully, and efforts to increase the number of circuits to accommodate growing demand for overseas voice communication were under way.

As has often been the case throughout history, the superiority of one innovative technology over others can evaporate suddenly with the appearance of yet another that promises greater return for one reason or another. Such was the case with the submarine cable. It was designed to provide multiple voice circuits to expedite instantaneous person-to-person communication among continents utilizing the national telephone networks in countries that would be reached via that cable.

While it provided that service reliably for many years, soon geosynchronous satellites high above the equator were able to offer the same service, but with much greater circuit capacity. Another advantage was the satellite’s unique ability to relay voice conversations to even the most remote locations on the face of the earth. In theory, an elaborate telephone network was not required for two parties—each located in some remote corner of the world—to communicate with each other. As long as each had a transmitter and receiver capable of supporting a relay via a communications satellite, telecommunications infrastructure was not required. Such a relay could span oceans as well as continents quite easily. This capability made the satellite extremely attractive to many countries that lacked adequate telecommunications infrastructure, and it was only a matter of time before it would be used extensively to relay transoceanic telephone conversations. Transatlantic telephone cable
Telecommunications;transatlantic cables

Further Reading

  • Brooks, John. Telephone: The First Hundred Years. New York: Harper & Row, 1976. This excellent corporate history of the Bell system includes many anecdotes and colorful stories about the early years of telephony, giving life and context to what could otherwise be described as a highly technical description of the birth and development of one of the world’s most remarkable companies. Includes a discussion of the evolution of transoceanic cable in the Bell Laboratories.
  • Danielian, Noorbar R. AT&T: The Story of Industrial Conquest. New York: Vanguard Press, 1939. A good look at some of the personalities involved in the development of the world’s largest telephone network. Provides a strong backdrop for gaining an understanding of how and why decisions were made regarding the adoption of technical innovations at AT&T through the years.
  • Hearn, Chester G. Circuits in the Sea: The Men, the Ships, and the Atlantic Cable. Westport, Conn.: Praeger, 2004. Details the laying of the initial transatlantic cable in the nineteenth century and looks ahead to the telephone cable of the twentieth century. Bibliographic references and index.
  • Millman, S., ed. A History of Engineering and Science in the Bell System: Communications Sciences, 1925-1980. Short Hills, N.J.: AT&T Bell Laboratories, 1984. Discusses the various foundations of applied physics in communications technology, including television, radio, lightwave transmission, and digital communications. Index.
  • Ress, Etta Schneider. Signals to Satellites in Today’s World. Mankato, Minn.: Creative Educational Society, 1965. This heavily illustrated book is a layperson’s overview of the evolution of communication technology over the centuries up to the mid-1960’s. Includes a good discussion of the history of transoceanic cable from the middle of the nineteenth century to the deployment of the first telephone cable in 1956. Illustrated.
  • Smits, F. M., ed. A History of Engineering and Science in the Bell System: Electronics Technology, 1925-1975. Indianapolis: AT&T Bell Laboratories, 1985. Reviews developments in electronics that have been incorporated into the design of long-distance cable and related equipment, including the transistor, integrated circuits, and optical devices. Index.

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