| 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 |
|---|---|---|---|
| 303-261 | Adams | Aurora, CO | Qwest Corporation |
| 303-262 | Denver | Denver, CO | AT&T Local |
| 303-263 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-264 | Arapahoe | Denver, CO | Teleport Communications America |
| 303-265 | Denver | Denver, CO | Qwest Corporation |
| 303-266 | Jefferson | Denver, CO | Usa Mobility Wireless |
| 303-267 | Denver | Denver, CO | Qwest Corporation |
| 303-268 | Denver | Denver, CO | Icg Telecom Group |
| 303-269 | Jefferson | Denver, CO | Qwest Corporation |
| 303-270 | Denver | Denver, CO | Qwest Corporation |
| 303-271 | Jefferson | Golden, CO | Qwest Corporation |
| 303-272 | Adams | Denver, CO | Qwest Corporation |
| 303-273 | Jefferson | Golden, CO | Qwest Corporation |
| 303-274 | Jefferson | Denver, CO | Qwest Corporation |
| 303-275 | Jefferson | Denver, CO | Qwest Corporation |
| 303-276 | Jefferson | Denver, CO | Convergent Communications |
| 303-277 | Jefferson | Golden, CO | Qwest Corporation |
| 303-278 | Jefferson | Golden, CO | Qwest Corporation |
| 303-279 | Jefferson | Golden, CO | Qwest Corporation |
| 303-280 | Adams | 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.