| District of Illinois area codes: 618 | |
|---|---|
| Country | United States |
| State/Province | Illinois |
| Major City | Belleville |
| Time Zone | Central (UTC-06:00) |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 618-366 | Randolph | Chester, IL | Southwestern Bell |
| 618-367 | Marion | Centralia, IL | Cellco Partnership DBA Verizon Wireless |
| 618-368 | Calhoun | Hardin, IL | Level 3 Communications |
| 618-369 | Madison | Collinsville, IL | American Messaging (am) |
| 618-370 | Macoupin | Medora, IL | Level 3 Communications |
| 618-371 | Perry | Tamaroa, IL | Level 3 Communications |
| 618-372 | Macoupin | Brighton, IL | Ameritech Illinois |
| 618-373 | Saline | Eldorado, IL | Aero Communications, Inc |
| 618-374 | Jersey | Elsah, IL | Ameritech Illinois |
| 618-375 | White | Grayville, IL | Frontier North |
| 618-376 | Jersey | Fieldon, IL | Citizens Telecom Co Illinois-frontier Citizens -il |
| 618-377 | Madison | Bethalto, IL | Ameritech Illinois |
| 618-378 | White | Norris City, IL | Frontier North |
| 618-379 | White | Norris City, IL | Delta Comms DBA Clearwave Communications |
| 618-380 | White | Carmi, IL | Delta Comms DBA Clearwave Communications |
| 618-381 | Madison | Collinsville, IL | Mci Worldcom Communications |
| 618-382 | White | Carmi, IL | Frontier North |
| 618-383 | White | Carmi, IL | Allied Wireless Communications LLC DBA Alltel-il |
| 618-384 | White | Carmi, IL | Frontier North |
| 618-385 | Perry | Tamaroa, IL | Level 3 Communications |
There are 692 prefixes, In the code area, the major cities are Alton, IL;Belleville, IL;Carbondale, IL;Collinsvil. The major city is Belleville.