Area codes 970 and 748 are telephone area codes in the North American Numbering Plan (NANP) for the western and northern parts of the U.S. of State of Colorado. The numbering plan area includes Aspen, Breckenridge, Durango, Estes Park, Fort Collins, Glenwood Springs, Grand Junction, Greeley, Loveland, Silverthorne, Steamboat Springs, and Vail.