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Castle Rock, CO is currently using two area codes 303 and 720. Castle Rock, CO utilizes an area code overlay in which
area codes 303 and 720 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary in Castle Rock because two different homes in the same geographic area can have the same
seven digit phone number but each would have a different area code. The area code overlay which is in use in Castle Rock, CO today was established in 1998.
Area Code 303 which is still in use in
Castle Rock, CO was one of the original area codes established in 1947. At that time it covered the entire state of Colorado. The area code has been split numerous times. Today, in addition to Castle Rock,
CO, area codes 303 and 720 serve the larger communities of Arvada, Aurora, Boulder, Brighton, Broomfield, Castlewood, Columbine, Commerce City, Denver, Englewood, Highlands Ranch, Ken Caryl, Lafayette,
Lakewood, Littleton, Longmont, Loveland, Northglenn, Parker, Southglenn, Thornton, Westminster and Wheat Ridge. |
