| 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 |
|---|---|---|---|
| 303-810 | Jefferson | Denver, CO | New Cingular Wireless PCS |
| 303-812 | Denver | Denver, CO | Qwest Corporation |
| 303-813 | Denver | Denver, CO | Qwest Corporation |
| 303-814 | Jefferson | Denver, CO | Qwest Corporation |
| 303-815 | Jefferson | Denver, CO | Interlink Adv Svc D/b/a Forethought.net |
| 303-816 | Jefferson | Denver, CO | Qwest Corporation |
| 303-817 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-818 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-819 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-820 | Denver | Denver, CO | Qwest Corporation |
| 303-821 | Jefferson | Denver, CO | Usa Mobility Wireless |
| 303-822 | Arapahoe | Byers, CO | Bijou Telephone Cooperative Association |
| 303-823 | Larimer | Lyons, CO | Qwest Corporation |
| 303-824 | Arapahoe | Denver, CO | Teleport Communications America |
| 303-825 | Denver | Denver, CO | Qwest Corporation |
| 303-826 | Jefferson | Denver, CO | Usa Mobility Wireless |
| 303-827 | Boulder | Longmont, CO | Icg Telecom Group |
| 303-828 | Jefferson | Denver, CO | Qwest Corporation |
| 303-829 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-830 | 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.