| 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 |
|---|---|---|---|
| 815-939 | Kankakee | Kankakee | Landline |
| 815-487 | Plainfield | Will | Landline |
| 815-770 | Harvard | Mchenry | Landline |
| 815-539 | Mendota | La Salle | Landline |
| 815-622 | Sterling | Whiteside | Landline |
| 815-916 | Newark | Kendall | Wireless |
| 815-669 | Mchenry | Mchenry | Landline |
| 815-434 | Ottawa | La Salle | Landline |
| 815-344 | Mchenry | Mchenry | Landline |
| 815-542 | Deer Grove | Whiteside | Landline |
| 815-556 | Plainfield | Will | Landline |
| 815-372 | Lockport | Will | Landline |
| 815-444 | Crystal Lake | Mchenry | Landline |
| 815-818 | Warren | Jo Daviess | Landline |
| 815-402 | Galena | Jo Daviess | Landline |
| 815-828 | Minooka | Grundy | Landline |
| 815-257 | Streator | La Salle | Wireless |
| 815-328 | Romeoville | Will | Landline |
| 815-379 | Walnut | Bureau | Landline |
| 815-608 | Rockford | Winnebago | Wireless |