| 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 |
|---|---|---|---|
| 303-363 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-364 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-365 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-366 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-367 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-368 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-369 | Arapahoe | Aurora, CO | Qwest Corporation |
| 303-370 | Denver | Denver, CO | Qwest Corporation |
| 303-371 | Denver | Denver, CO | Qwest Corporation |
| 303-372 | Denver | Denver, CO | Qwest Corporation |
| 303-373 | Denver | Denver, CO | Qwest Corporation |
| 303-374 | Arapahoe | Denver, CO | Teleport Communications America |
| 303-375 | Denver | Denver, CO | Qwest Corporation |
| 303-376 | Denver | Denver, CO | Icg Telecom Group |
| 303-377 | Denver | Denver, CO | Qwest Corporation |
| 303-378 | Jefferson | Denver, CO | New Cingular Wireless PCS |
| 303-379 | Arapahoe | Denver, CO | Teleport Communications America |
| 303-380 | Denver | Denver, CO | Qwest Corporation |
| 303-381 | Denver | Denver, CO | Icg Telecom Group |
| 303-382 | 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.