| District of Colorado area codes: 720 | |
|---|---|
| Country | United States |
| State/Province | Colorado |
| Major City | Denver |
| Time Zone | Mountain |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 720-578 | Denver | Denver, CO | Qwest Corporation |
| 720-579 | Denver | Denver, CO | Xo Colorado |
| 720-580 | Weld | Keenesburg, CO | Bandwidth.com Clec |
| 720-581 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-583 | Jefferson | Denver, CO | 360networks (usa) Inc. |
| 720-585 | Jefferson | Denver, CO | Commnet Wireless |
| 720-587 | Denver | Denver, CO | AT&T Local |
| 720-588 | Denver | Denver, CO | 365 Wireless |
| 720-589 | Arapahoe | Aurora, CO | T-mobile Usa |
| 720-590 | Jefferson | Denver, CO | 360networks (usa) Inc. |
| 720-593 | Jefferson | Denver, CO | Tw Telecom Of Colorado LLC |
| 720-596 | Arapahoe | Denver, CO | Teleport Communications America |
| 720-599 | Denver | Denver, CO | Eschelon Telecom Of Colorado |
| 720-600 | Boulder | Longmont, CO | 360networks (usa) Inc. |
| 720-606 | Weld | Fort Lupton, CO | New Cingular Wireless PCS |
| 720-608 | Clear Creek | Idaho Springs, CO | Bandwidth.com Clec |
| 720-609 | New Cingular Wireless PCS | ||
| 720-612 | Jefferson | Denver, CO | Sprint Spectrum L.p. |
| 720-613 | Weld | Hudson, CO | Mcimetro Access Transmission Services LLC |
| 720-618 | Cellco Partnership DBA Verizon Wireless |
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.