Area Code Atlas

NANP - SPLIT OF THE 303 NUMBERING PLAN AREA

Split of 303 to create 719

On March 5, 1988, area code 303 was split to create area code 719. The new 719 area code served southeastern Colorado, including Colorado Springs, Pueblo, Leadville, and Alamosa, while 303 continued to serve the rest of the state.

NPA 303 split to create 719

The 303 area code was split on March 5, 1988, reducing its coverage to exclude southeastern Colorado, which became area code 719. The split was necessary to address number exhaustion and to serve southeastern Colorado, including Colorado Springs, Pueblo, Leadville, and Alamosa, while 303 continued to serve Denver, Boulder, and northern regions.

Mandatory dialing for 719 and 303 after split

Permissive dialing for both 303 and 719 ended on April 4, 1988, requiring callers to use the correct area code for all calls within the affected regions. This marked the completion of the transition to the new area code boundaries.

NANP-SPLIT OF 303 (COLORADO) NUMBERING PLAN AREA (NPA)

Split of 303 to create 970

On April 2, 1995, area code 303 was split to create area code 970. The new 970 area code served northeastern and western Colorado, including Fort Collins, Grand Junction, Vail, and Aspen, while 303 was reduced to the Denver-Boulder area.

NPA 303 split to create 970

The 303 area code was split on April 2, 1995, with the creation of 970 for northeastern and western Colorado. The 303 code was then limited to the Denver-Boulder metropolitan area. Area code 970 was established as a geographic split from 303, serving the western and northern regions of Colorado.

Declaration of Jeopardy Situation in NPA 303 (Colorado)

NANP-Overlay of 303 (Colorado) Numbering Plan Area (NPA) with 720 NPA

Overlay of 720 on 303 and start of 10-digit dialing

On August 31, 1998, area code 720 was overlaid on the existing 303 area code in the Denver area. This overlay required residents to begin dialing ten digits for all local calls, even for calls to neighbors. The overlay was implemented to avoid changing existing phone numbers and to provide additional numbering resources.

Mandatory 10-digit dialing for 303/720 overlay

Ten-digit dialing became mandatory in the Denver area on August 31, 1998, coinciding with the overlay of area code 720 on 303. This change was made to avoid changing existing phone numbers and to accommodate the new overlay.

NPA 720 overlay introduced on 303

Area code 720 was introduced on September 1, 1998, as an overlay to the 303 area to provide additional numbering resources in the Denver-Boulder region, requiring ten-digit dialing for all local calls.

First celebration of 303 Day

On March 3, 2009, the first 303 Day was celebrated in Colorado. The unofficial holiday, named after the 303 area code, is marked by local businesses offering discounts and events to celebrate Colorado pride.

NPA 983 relief planned for 303/720 overlay complex

The Colorado Public Utilities Commission approved the addition of area code 983 on May 21, 2021, as relief for the 303/720 overlay complex due to projected numbering exhaustion by 2023.

NPA 983 overlay on 303/720 announced

NPA 983 to Overlay NPA 303/720 (Colorado)

NPA 983 activated as overlay on 303/720

Area code 983 was activated on June 17, 2022, as an overlay to the existing 303 and 720 area codes in the Denver-Boulder area, expanding the numbering resources available to the region.