NIST and the U.S. Naval Observatory jointly operate a web site that provides the Official U.S. Time at http://www.time.gov. Readings from the clocks of these two agencies contribute to world time, called Coordinated Universal Time (UTC).
NIST offers several alternatives for accessing NIST time by telephone. To hear the same WWV time announcements by phone that you would hear using a shortwave radio, call (303) 499-7111. This is not a toll-free call, except in the local Boulder/Denver, CO, area. Your call will be automatically cut off after approximately 3 minutes. To hear the similar WWVH time announcements from Hawaii, call (808) 335-4363.
To synchronize your computer's clock to NIST time see Set Your Computer's Clock to NIST Time.
To learn more about NIST's new super accurate atomic fountain clock--which shares the distinction with a similar instrument in Paris as the most accurate clock in the world--see this press release and accompanying illustrations.