IEEE Milestone Honors the First Transpacific Cable

Built in the early 1960s, TPC-1 opened communications between the United States and Japan

16 January 2015

Before 1964, telephone calls could not be made between the United States and Japan. Short-wave radio provided the only method of communication between the two countries, and the transmission was unreliable, often had poor sound, and could be interrupted by harsh weather. 

To improve the speed and quality of the communications, the two countries signed an agreement in 1962 to build a US $83 million coaxial cable that would traverse the Pacific Ocean. Two years later, the Transpacific Cable System No. 1, or TPC-1, was complete. It connected Japan and Hawaii and linked with an existing cable that ran from Hawaii to San Francisco.

With the cable, telephone calls could be made from Tokyo directly to Bermuda, Jamaica, Mexico, Puerto Rico, the United States, and the Virgin Islands. It also triggered the rapid development of undersea telephone cable networks throughout East Asia, increasing the communications capacity of Asia, the United States, and Europe.

TPC-1 was recognized in November with an IEEE Milestone. Administered by the IEEE History Center, the Milestone program recognizes outstanding technical developments around the world.


The design and construction of TPC-1 involved two U.S. telecommunications companies—AT&T, in New York City, and the Hawaiian Telephone Co., in Honolulu—and Japan’s Kokusai Denshin Denwa (KDDI), in Tokyo. Nihon Kaiteidensen Co. (now Ocean Cable and Communications Corp.), a cable manufacturer, in Osaka, Japan, built some portions of TPC-1 under AT&T’s supervision.

The four companies faced a monumental task when they got to work in March 1962. TPC-1 would connect with three existing undersea cable lines: HAW-1 and HAW-2, which went from Hawaii to San Francisco, and the Guam-Philippines Cable, which linked with Compac—the cable joining Canada, New Zealand, and Australia.

The TPC-1 cable had to cross the Mariana Trench—the deepest part of the world’s oceans. Approximately 11 kilometers deep and 2,500 km long, the trench is south of Japan near Guam. It is only 69 km wide. To navigate this area as well as other complicated features of the seafloor, ocean geologists from the United States and Japan examined hydrographic surveys obtained by the Japanese Oceanography Service to determine a safe and stable route for the cable.

The coaxial cable itself not only had to withstand a deep-sea environment but also had to satisfy the voice quality standards set forth by the CCITT, an organization that develops standards for telecommunications equipment and systems, now known as the ITU-T (for Telecommunication Standardization Sector of the International Telecommunications Union). Repeaters were installed every 32 km to boost the signal and provide clearer sound. The cable was also equipped with echo suppressors and international telephone exchange switches, which were also built in Japan by Nihon Kaiteidensen.

The last stretch of the TPC-1, the 2,670-km connection between Japan and Guam, was completed in May 1964. The Japanese end of the cable emerged from the ocean near Ōiso, about 50 miles southwest of Tokyo.


TPC-1 went into service on 19 June 1964. That day, U.S. President Lyndon B. Johnson telephoned Japan’s Prime Minister Hayato Ikeda from the White House. Ikeda received the call at the Imperial Hotel, in Tokyo. A New York Times reporter in the room with the prime minister wrote that the “reception of the first call was excellent—the audience gathered in the hotel heard President Johnson’s voice, magnified on a loudspeaker, come in almost as clearly as if he had been speaking on a public address system in the same room.” However, the exchange between the two men was delayed a few minutes as the signal went from Japan to Washington and returned, so that “laughter filled the awkward silence” as the audience in Tokyo waited for the president’s responses.

The success of TPC-1 also spurred the construction of several more undersea cables around Asia. And in the long run, TPC-1 provided the foundation for today’s fiber-optic submarine cables over which people from around the world reach each other by telephone almost instantly. 

A ceremony for the Milestone was held on 11 November. A plaque mounted on a wall of KDDI’s headquarters, in Tokyo, reads:

The first transpacific undersea coaxial telephone cable linking Japan, Hawaii, and the U.S. mainland was completed in 1964. President Lyndon B. Johnson and Prime Minister Hayato Ikeda inaugurated this communications link on 19 June 1964. This joint project involving American Telephone and Telegraph, Hawaiian Telephone Company, and Kokusai Denshin Denwa improved global communication and contributed to deep-water submarine cable technologies.

This article was written with assistance from the IEEE History Center, which is funded by donations to the IEEE Foundation.

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