| General Information about Area Code 815 | |
|---|---|
| Country | United States |
| State / Province / Territory | Illinois |
| Major City | Rockford |
| Time Zone | Central (UTC-06:00) |
| Prefix | Primary City | County | Phone Type |
|---|---|---|---|
| 815-409 | Joliet | Will | Wireless |
| 815-949 | Cabery | Ford | Landline |
| 815-729 | Joliet | Will | Landline |
| 815-898 | Hanover | Jo Daviess | Landline |
| 815-318 | Morris | Grundy | Landline |
| 815-843 | Ashton | Lee | Landline |
| 815-615 | Mendota | La Salle | Landline |
| 815-924 | Prophetstown | Whiteside | Landline |
| 815-219 | Crystal Lake | Mchenry | Wireless |
| 815-762 | Dekalb | Dekalb | Wireless |
| 815-404 | Crystal Lake | Mchenry | Wireless |
| 815-965 | Rockford | Winnebago | Landline |
| 815-733 | Plainfield | Will | Landline |
| 815-603 | Kankakee | Kankakee | Wireless |
| 815-274 | Joliet | Will | Wireless |
| 815-355 | Wonder Lake | Mchenry | Wireless |
| 815-227 | Rockford | Winnebago | Landline |
| 815-363 | Mchenry | Mchenry | Landline |
| 815-204 | Crystal Lake | Mchenry | Wireless |
| 815-290 | Minooka | Grundy | Landline |