| District of Colorado area codes: 720 | |
|---|---|
| Country | United States |
| State/Province | Colorado |
| Major City | Denver |
| Time Zone | Mountain |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 720-323 | Jefferson | Denver, CO | T-mobile Usa |
| 720-324 | Arapahoe | Aurora, CO | Comcast Phone Of Colorado |
| 720-325 | Denver | Aurora, CO | T-mobile Usa |
| 720-326 | Jefferson | Denver, CO | New Cingular Wireless PCS |
| 720-327 | Jefferson | Denver, CO | Leap Wireless Intl DBA Cricket Comm |
| 720-328 | Denver | Denver, CO | Comcast Phone Of Colorado |
| 720-329 | Jefferson | Denver, CO | Leap Wireless Intl DBA Cricket Comm |
| 720-330 | Denver | Denver, CO | Icg Telecom Group |
| 720-331 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-332 | Jefferson | Denver, CO | Mcimetro Access Transmission Services LLC |
| 720-333 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-334 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-335 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-336 | Weld | Keenesburg, CO | Bandwidth.com Clec |
| 720-337 | Jefferson | Denver, CO | Qwest Corporation |
| 720-338 | Jefferson | Denver, CO | Leap Wireless Intl DBA Cricket Comm |
| 720-339 | Denver | Denver, CO | Sprint Spectrum L.p. |
| 720-340 | Boulder | Longmont, CO | Cellco Partnership DBA Verizon Wireless |
| 720-341 | Jefferson | Denver, CO | T-mobile Usa |
| 720-342 | Jefferson | Denver, CO | AT&T Local |
There are 519 prefixes, In the code area, the major cities are Arvada, CO;Aurora, CO;Boulder, CO;Brighton, CO;Bro. The major city is Denver.