Illinois · Central Time
815 Area Code
Area code 815 is in Illinois, serving northern Illinois outside the Chicago core, including Rockford, Joliet and Kankakee. It is in the Central Time zone. It shares its territory with overlay code 779, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 815 area code?
815 is a Illinois area code covering northern Illinois outside the Chicago core, including Rockford, Joliet and Kankakee. In the wider directory it sits in the Midwest region.
Cities in the 815 area code
- Rockford
- Joliet
- Kankakee
- DeKalb
- Crystal Lake
- McHenry
- Belvidere
- Freeport
- Woodstock
- Ottawa
- Sterling
- Dixon
- LaSalle
- Bradley
Counties served by 815
Winnebago County, Will County, Kankakee County, DeKalb County, McHenry County, LaSalle County, Boone County, Stephenson County, Whiteside County and Lee County.
815 overlay codes and dialing
The 815 territory is covered by an overlay of 2 area codes: 779, 815. All of them serve the same geographic area, and the original code is 815. Because more than one code covers the same ground, 10-digit dialing is mandatory — you must dial the area code for every local call. New phone lines may be assigned any of these codes.
History of the 815 area code
815 is one of the original area codes assigned in 1947, when AT&T and Bell Laboratories created the North American Numbering Plan and divided the country into the first 86 numbering plan areas. It has served the Rockford area ever since, with 779 later added as an overlay to supply more numbers.
Is 815 a scam or spam risk?
815 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 815 number on your screen is no guarantee the caller is in Rockford, IL or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Other Illinois area codes
Explore more
See every code in Illinois, compare codes across the Midwest region, or view all Central Time codes. You can also browse the 8XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
815 area code FAQ
Where is the 815 area code?
The 815 area code is in Illinois, covering northern Illinois outside the Chicago core, including Rockford, Joliet and Kankakee, in the Midwest region.
What cities are in the 815 area code?
Cities in the 815 area code include Rockford, Joliet, Kankakee, DeKalb, Crystal Lake, McHenry, Belvidere, Freeport, Woodstock and Ottawa.
What time zone is 815 in?
815 is in the Central Time zone.
What is the overlay for the 815 area code?
815 shares its territory with 779. Both codes (779, 815) serve the same area, so 10-digit dialing is required for every call.
When did the 815 area code start?
815 went into service on January 1, 1947 as one of the original 1947 North American area codes.
Do I have to dial 10 digits for 815?
Yes. Because 815 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 815 a toll-free or premium code?
No. 815 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.