| District of Colorado area codes: 303 | |
|---|---|
| Country | United States |
| State/Province | Colorado |
| Major City | Denver |
| Time Zone | Mountain (UTC-07:00) |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 303-301 | Denver | Denver, CO | Icg Telecom Group |
| 303-302 | Jefferson | Denver, CO | Xo Colorado |
| 303-304 | Weld | Fort Lupton, CO | New Cingular Wireless PCS |
| 303-305 | Denver | Denver, CO | Mcimetro Access Transmission Services LLC |
| 303-306 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-307 | Denver | Denver, CO | Qwest Corporation |
| 303-308 | Denver | Denver, CO | Qwest Corporation |
| 303-309 | Jefferson | Denver, CO | Global Crossing Local Services-co |
| 303-310 | Jefferson | Denver, CO | Contact Paging Of Colorado |
| 303-312 | Denver | Denver, CO | Qwest Corporation |
| 303-313 | Denver | Denver, CO | Qwest Corporation |
| 303-314 | Denver | Denver, CO | Qwest Corporation |
| 303-315 | Denver | Denver, CO | Qwest Corporation |
| 303-316 | Jefferson | Denver, CO | Qwest Corporation |
| 303-317 | Adams | Aurora, CO | Qwest Corporation |
| 303-318 | Denver | Denver, CO | Qwest Corporation |
| 303-319 | Jefferson | Denver, CO | Elbert County Wireless |
| 303-320 | Denver | Denver, CO | Qwest Corporation |
| 303-321 | Denver | Denver, CO | Qwest Corporation |
| 303-322 | Denver | Denver, CO | Qwest Corporation |
There are 783 prefixes, In the code area, the major cities are Arvada, CO;Aurora, CO;Boulder, CO;Brighton, CO;Bro. The major city is Denver.