| 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 |
|---|---|---|---|
| 331-301 | Aurora | Kane | Landline |
| 331-206 | Aurora | Kane | Wireless |
| 331-304 | Hanover Park | Cook | Wireless |
| 331-250 | Aurora | Kane | Wireless |
| 331-801 | Downers Grove | Dupage | Landline |
| 331-465 | West Chicago | Dupage | Wireless |
| 331-422 | Geneva | Kane | Landline |
| 331-825 | Kane | Kane | - |
| 331-212 | Aurora | Kane | Landline |
| 331-208 | Aurora | Kane | Wireless |
| 331-701 | Naperville | Dupage | Wireless |
| 331-425 | Aurora | Kane | Wireless |
| 331-643 | Aurora | Kane | Wireless |
| 331-310 | Big Rock | Kane | Landline |
| 331-218 | Wheaton | Dupage | Wireless |
| 331-240 | West Chicago | Dupage | Landline |
| 331-223 | Geneva | Kane | Wireless |
| 331-256 | Aurora | Kane | Wireless |
| 331-213 | Naperville | Dupage | Wireless |
| 331-220 | Aurora | Kane | Wireless |