Area code 815: where it is and who calls from it
Area code 815 is in Illinois.
Illinois (much of northern Illinois outside Chicago and its immediate surrounding suburbs: Rockford and its suburbs, Belvidere, La Salle, Peru, DeKalb, Sycamore, Freeport, Dixon, Sterling, Rock Falls, Ottawa, Morris, Princeton, Mendota, Rochelle, Sandwich, Streator, Pontiac, Kankakee, and some outlying Chicago suburbs such as Harvard, McHenry, Crystal Lake, Woodstock, Plainfield, Joliet, Romeoville, Lockport, New Lenox, Frankfort, Minooka, Channahon, and Shorewood)
| Where | Illinois |
|---|---|
| Time zone | Central Time ยท local time |
| In service since | 1947 |
| Overlay | Yes, with 779 |
| Prefixes assigned | 786 of 792 possible (99%) |
Overlay: 815 covers the same area as 779. Overlay areas use 10-digit dialing, so a seven-digit number alone won't connect, and neighbors can have different area codes.
Where 815 numbers started
Every prefix is assigned to a rate center, the local calling area it was set up in. These are the biggest in 815, with how many prefixes each has.
Plus 140 smaller rate centers.
Who holds 815 numbers
- Mobile carrier 22%
- Local phone company 43%
- Internet / business phone carrier 22%
- Paging service 2%
- Phone company 12%
| Carrier | Type | Prefixes | Share |
|---|---|---|---|
| Frontier | Local phone company | 160 | 20% |
| AT&T (local phone) | Local phone company | 159 | 20% |
| Level 3 (Lumen) | Internet / business phone carrier | 76 | 10% |
| Verizon Wireless | Mobile carrier | 50 | 6% |
| Aero North Communications | Phone company | 43 | 5% |
| AT&T Mobility | Mobile carrier | 42 | 5% |
| T-Mobile (including Sprint) | Mobile carrier | 40 | 5% |
| UScellular | Mobile carrier | 23 | 3% |
| Teleport Communications America | Internet / business phone carrier | 22 | 3% |
| Mediacom Telephony Of Illinois | Internet / business phone carrier | 17 | 2% |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number.
States served: Illinois.
Other area codes in Illinois
217 224 309 312 331 447 464 618 630 708 730 773 779 847 861 872
Got a call from 815?
An area code tells you where a number was first assigned, not where the caller is. People keep their numbers when they move, and scammers can fake any number. If you weren't expecting the call, let it go to voicemail.
If the call shows a 815 number that matches the first six digits of your own, that's often neighbor spoofing. Use the box above to check the full number.
Area code facts from the NANPA area code database (updated 10/06/2026); prefixes and carriers from NANPA's central office code records (updated 2026-10-10). Place description adapted from Wikipedia, CC BY-SA 4.0.