| 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 |
|---|---|---|---|
| 303-221 | Denver | Denver, CO | Qwest Corporation |
| 303-222 | Denver | Denver, CO | Mcimetro Access Transmission Services LLC |
| 303-223 | Jefferson | Denver, CO | Global Crossing Local Services-co |
| 303-224 | Denver | Denver, CO | Qwest Corporation |
| 303-225 | Jefferson | Denver, CO | Global Crossing Local Services-co |
| 303-226 | Denver | Denver, CO | Icg Telecom Group |
| 303-227 | Denver | Denver, CO | Qwest Corporation |
| 303-228 | Denver | Denver, CO | Icg Telecom Group |
| 303-229 | Jefferson | Denver, CO | Cellco Partnership DBA Verizon Wireless |
| 303-230 | Jefferson | Denver, CO | Usa Mobility Wireless |
| 303-231 | Jefferson | Denver, CO | Qwest Corporation |
| 303-232 | Jefferson | Denver, CO | Qwest Corporation |
| 303-233 | Jefferson | Denver, CO | Qwest Corporation |
| 303-234 | Jefferson | Denver, CO | Qwest Corporation |
| 303-235 | Jefferson | Denver, CO | Qwest Corporation |
| 303-236 | Jefferson | Denver, CO | Qwest Corporation |
| 303-237 | Jefferson | Denver, CO | Qwest Corporation |
| 303-238 | Jefferson | Denver, CO | Qwest Corporation |
| 303-239 | Jefferson | Denver, CO | Qwest Corporation |
| 303-240 | Jefferson | Denver, CO | Usa Mobility Wireless |
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.