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.

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.

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