Area Code 303
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Area Code 303

Area code 970Area codes 303 and 720Area code 719Area code 785Area code 308Area code 307Area code 435Area code 928Area code 575Area code 505Area code 580Area code 620
Clickable map of Colorado area codes in blue (with bordering states).[1]

Area codes 303 and 720 are telephone area codes in the North American Numbering Plan for the north-central portion of the state of Colorado. The numbering plan area comprises Denver and Boulder, as well as their surrounding suburbs, including Lakewood, Littleton, Longmont, Aurora, and Castle Rock. Area code 303 is the original area code, while area code 720 was added to form an overlay plan for the area, meaning that the same geographic service area is served by both area codes and that ten-digit dialing is required for all calls made within the service area.


Area code 303 was one of the original area codes assigned in 1947, and originally served the entire state of Colorado. Despite Colorado's growth during the second half of the 20th century, especially in the Denver area, it remained the sole area code in Colorado for over 40 years. By the late 1980s, an impending number shortage made a split necessary. On March 5, 1988, southeastern Colorado, including Colorado Springs and Pueblo, received area code 719.[2] The northeastern and western portions of area code 303, including Fort Collins, Grand Junction, Vail and Aspen, switched to area code 970 on April 2, 1995, reducing 303 to the Denver-Boulder area.[3] With the 1995 split, 303 was the only Colorado area code that did not border another state.

The 1995 split was intended as a long-term solution. However, within two years 303 was close to exhaustion once again. The Front Range is home not only to most of Colorado's landlines, but also most of the state's cell phones, fax machines and pagers. To solve this problem, area code 720 was activated on September 1, 1998 in the same service area to create an overlay plan.[4] A third area code will likely be required in the Denver metropolitan area by 2023 according to current projections.[5]

Local calling

The 303/720 area is one of the largest toll-free calling zones in the western United States. With the exception of Roggen, Brighton, and Wiggins,[6] no long-distance charges are applied to any calls made from one phone to another in the area.

With the exception of Roggen, all users in the 303/720 area must dial all ten digits to reach a destination phone.

See also


  1. ^ "Area Codes Map, Colorado". NANPA. Retrieved 2018.
  2. ^ NANP Information Letter 87-03-045 (1987-03-27), retrieved 2020-08-29
  3. ^ NANPA Information Letter 94/09-012 (1994-09-21) retrieved 2020-08-29
  4. ^ MICHAEL LOVELL (August 31, 1998). "10-Digit Dialing Hits Denver Area". Reuters. Retrieved 2019.
  5. ^
  6. ^ "Local Calling Guide". Retrieved 2012.

External links

Colorado area codes: 303/720, 719, 970
North: 970
West: 970 Area code 303 / 720 East: 719
South: 719

Coordinates: 40°N 105°W / 40°N 105°W / 40; -105

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.



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