| 303 | Colorado (Boulder, Longmont, Aurora, Denver and central Colorado, overlays with 720) More information at: Area Code 303 Phone Number Blocks |
| 719 | Colorado (Leadville, Pueblo, Colorado Springs, Trinidad, Rocky Ford, La Junta and southeastern Colorado) More information at: Area Code 719 Phone Number Blocks |
| 720 | Colorado (Boulder, Longmont, Aurora, Denver and central Colorado, overlays with 303) More information at: Area Code 720 Phone Number Blocks |
| 970 | Colorado (Aspen, Durango, Grand Junction, Fort Collins and northern and western Colorado) More information at: Area Code 970 Phone Number Blocks |
