improved mobile telephone service

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Ahura Mazda - relief of the Zoroastrian god Ahura Mazda at the ancient ruins of Persepolis in Iran. Also known as Ormazd Zoroastrianism,

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Vietnam War. U.S. President Lyndon B. Johnson awards the Distinguished Service Cross to First Lieutenant Marty A. Hammer, during a visit to military personnel, Cam Ranh Bay, South Vietnam, October 26, 1966. President Johnson

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The Castillo, a Toltec-style pyramid, rises 79 feet (24 meters) above the plaza at Chichen Itza in Yucatan state, Mexico. The pyramid was built after invaders conquered the ancient Maya city in the tenth century.

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Gills of three old specimens of webcap fungus (Cortinarius) in Gloucestershire, South West England. toxic, fungi, poisonous mushroom

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A Factory Interior, watercolor, pen and gray ink, graphite, and white goache on wove paper by unknown artist, c. 1871-91; in the Yale Center for British Art. Industrial Revolution England

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African Americans demonstrating for voting rights in front of the White House as police and others watch, March 12, 1965. One sign reads, "We demand the right to vote everywhere." Voting Rights Act, civil rights.

Timeline of the American Civil Rights Movement

Space race (1957-1969) infographic between United States (U.S.) and Russia. America, Soviet Union, U.S.S.R., space exploration

Timeline of the Space Race, 1957–69

improved mobile telephone service

telecommunications

Also known as: IMTS

Learn about this topic in these articles:

mobile telephone

In mobile telephone: Development of cellular systems
In 1964 AT&T introduced the improved mobile telephone service (IMTS). This provided full duplex operation, automatic dialing, and automatic channel searching. Initially 11 channels were provided, but in 1969 an additional 12 channels were made available. Since only 11 (or 12) channels were available for all users of the system…
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