| District of Illinois area codes: 331 | |
|---|---|
| Country | United States |
| State/Province | Illinois |
| Major City | Lemont |
| Time Zone | Central |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 331-332 | Dupage | Naperville, IL | Cricket Communications |
| 331-333 | Dupage | Naperville, IL | Cricket Communications |
| 331-422 | Kane | Saint Charles, IL | Level 3 Communications |
| 331-425 | Kane | Aurora, IL | T-mobile Usa |
| 331-431 | Kane | Aurora, IL | Bandwidth.com Clec |
| 331-442 | Kane | Saint Charles, IL | Cellco Partnership DBA Verizon Wireless |
| 331-444 | Dupage | Naperville, IL | Cellco Partnership DBA Verizon Wireless |
| 331-452 | Kane | Aurora, IL | Cellco Partnership DBA Verizon Wireless |
| 331-454 | Kane | Aurora, IL | Cricket Communications |
| 331-456 | Dupage | Roselle, IL | First Communications LLC |
| 331-457 | Dupage | Naperville, IL | Cellco Partnership DBA Verizon Wireless |
| 331-462 | Dupage | Lombard, IL | Xo Illinois |
| 331-465 | Dupage | West Chicago, IL | New Cingular Wireless PCS |
| 331-472 | Dupage | Naperville, IL | T-mobile Usa |
| 331-481 | Dupage | Downers Grove, IL | Cellco Partnership DBA Verizon Wireless |
| 331-551 | Dupage | Lombard, IL | Cricket Communications |
| 331-575 | Kane | Aurora, IL | Sprint Spectrum L.p. |
| 331-588 | Kane | Saint Charles, IL | New Cingular Wireless PCS |
| 331-625 | Dupage | Downers Grove, IL | Cellco Partnership DBA Verizon Wireless |
| 331-642 | Dupage | Elmhurst, IL | Bandwidth.com Clec |
There are 75 prefixes, In the code area, the major cities are Addison, IL;Aurora, IL;Bartlett, IL;Batavia, IL;Be. The major city is Lemont.