| General Information about Area Code 331 | |
|---|---|
| Country | United States |
| State / Province / Territory | Illinois |
| Major City | Lombard |
| Time Zone | Central (UTC-06:00) |
| Prefix | Primary City | County | Phone Type |
|---|---|---|---|
| 331-332 | Naperville | Dupage | Wireless |
| 331-806 | Wheaton | Dupage | Landline |
| 331-201 | Downers Grove | Dupage | Wireless |
| 331-276 | Geneva | Kane | Wireless |
| 331-303 | Elburn | Kane | Landline |
| 331-551 | Lombard | Dupage | Wireless |
| 331-588 | Geneva | Kane | Wireless |
| 331-901 | Geneva | Kane | Landline |
| 331-333 | Naperville | Dupage | Wireless |
| 331-826 | Elmhurst | Dupage | Wireless |
| 331-979 | Elmhurst | Dupage | Landline |
| 331-203 | Aurora | Kane | Wireless |
| 331-215 | Naperville | Dupage | Wireless |
| 331-254 | Sugar Grove | Kane | Wireless |
| 331-575 | Aurora | Kane | Wireless |
| 331-998 | - | - | - |
| 331-888 | Warrenville | Dupage | Landline |
| 331-302 | Aurora | Kane | Wireless |
| 331-703 | West Chicago | Dupage | Wireless |
| 331-431 | Aurora | Kane | Wireless |