A brother and sister in San Francisco, California, talk to their parents on the other side of the country in 1916. This family conversation would have been impossible just two years earlier.

Photograph by L.W. Harris, National Geographic

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  • On January 25, 1915, Alexander Graham Bell made the first transcontinental telephone call. Calling from New York City, Bell was heard by his assistant, Thomas Watson, more than 4,023 kilometers (2,500 miles) away in San Francisco: “Mr. Watson, come here, I want you.” This was an important milestone in the development of telecommunications technology. A device was revolutionary—it transformed sound into electrical signals, transmitted those signals through a wire, and then changed them back to sound again. This technology allowed business, industry, and government to communicate instantaneously by voice across extremely long distances.

    Today, more than 4 billion people on the planet regularly use a telephone, either landline models similar to Bell’s early design, or wireless and smartphones. Increasingly, voice communications are conducted over the Internet.

  • Term Part of Speech Definition Encyclopedic Entry
    device Noun

    tool or piece of machinery.

    electrical grid Noun

    network of cables or other devices through which electricity is delivered to consumers. Also called a power grid.

    government Noun

    system or order of a nation, state, or other political unit.

    industry Noun

    activity that produces goods and services.

    instantaneously Adverb

    happening very quickly, in an instant.

    milestone Noun

    important event or stage in development.

    revolutionary Adjective

    new or innovative.

    smartphone Noun

    mobile telephone with additional features, such as a web browser or music playing device.

    technology Noun

    the science of using tools and complex machines to make human life easier or more profitable.

    telecommunications Noun

    the science and technology of sending and receiving information over long distances using electric, radio, or light signals.

    telephone Noun

    electronic tool and system for communication by sound or speech.

    transcontinental Adjective

    extending across an entire continent.

    transform Verb

    to change in appearance or purpose.

    transmission Noun

    broadcasting of electromagnetic signals, such as radio waves, from a transmitter to a receiver.