Area codes 970 and 748 are telephonearea codes in theNorth American Numbering Plan (NANP) for the western and northern parts of theU.S.state of Colorado. Thenumbering plan area includesAspen,Breckenridge,Durango,Estes Park,Fort Collins,Glenwood Springs,Grand Junction,Greeley,Loveland,Silverthorne,Steamboat Springs, andVail.
Area code 970 was established on April 2, 1995 in anarea code split ofarea code 303, which was retained by theDenver metropolitan area.[2]
On October 17, 2020, a federal law was enacted in the United States that established the short dialing code988 for theNational Suicide Prevention Lifeline. In compliance, theFederal Communications Commission ordered telecommunication carriers of 83 area codes, including 970, to transition toten-digit dialing, even when the area code was not involved in anoverlay complex, Area code 970 has PCS telephone numbers assigned for the central office code 988 in the Fort Collins exchange.[3] Per the timeline set by the North American Numbering Plan Administrator, permissive dialing began on April 24, 2021 and ten-digit dialing has been required from October 24, 2021.[4]
In 2023, the North American Numbering Plan Administrator estimated that area code 970 would reach numbering exhaustion by 2026. On December 18, 2023, theColorado Public Utilities Commission approved the addition ofarea code 748 for the all-services distributed overlay of NPA 970.[5] The overlay complex was activated on July 7, 2025.[6] No central office codes of area code 748 may be installed before complete exhaustion of area code 970.
| North:307,308 | ||
| West:435 | 748/970 | East:303/720/983,719,785 |
| South:303/720/983,505,575,719 | ||
| Kansas area codes:316,620,785,913 | ||
| Nebraska area codes:308,402/531 | ||
| New Mexico area codes:505,575 | ||
| Utah area codes:385/801,435 | ||
| Wyoming area codes:307 | ||
