| 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 |
|---|---|---|---|
| 815-884 | Harvard | Mchenry | Landline |
| 815-312 | Rockford | Winnebago | Landline |
| 815-749 | Rockford | Winnebago | Wireless |
| 815-715 | Joliet | Will | Wireless |
| 815-840 | Stockton | Jo Daviess | Landline |
| 815-732 | Oregon | Ogle | Landline |
| 815-479 | Crystal Lake | Mchenry | Landline |
| 815-394 | Rockford | Winnebago | Landline |
| 815-499 | Sterling | Whiteside | Wireless |
| 815-704 | South Beloit | Winnebago | Landline |
| 815-592 | Bradley | Kankakee | Wireless |
| 815-272 | Joliet | Will | Landline |
| 815-604 | Franklin Grove | Lee | Landline |
| 815-692 | Fairbury | Livingston | Landline |
| 815-331 | Mchenry | Mchenry | Landline |
| 815-584 | Dwight | Livingston | Landline |
| 815-996 | Savanna | Carroll | Wireless |
| 815-955 | Joliet | Will | Wireless |
| 815-735 | Joliet | Will | Wireless |
| 815-718 | Sterling | Whiteside | Wireless |