The 815 area code covers Rockford, Joliet and 186 more places in Illinois.
Area code 815 is in Illinois, on Central Time. In the 815 area, phone numbers are given out most in Will County, then Winnebago and McHenry counties. It has been in service since 1947. 779 covers the same area, so two neighbours can have different area codes.
- Where
- 8 counties in Illinois, mostly Will County, Winnebago County and McHenry County
- Time zone
- Central Time
- In service since
- 1947, one of the original area codes
- Shares its area with
- 779 (since 2007)
- Prefixes in use
- 786
- How to dial
- Local calls need 1, then the area code, then the number: 1-815-555-0142.
Find out who called you from an 815 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (815) number is on today, use our free carrier lookup.
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Rockford holds 12% of the phone prefixes in area code 815.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 786 prefixes in use shows where 815 numbers are actually given out.
- Rockford91 prefixes, 12%
- Joliet62 prefixes, 8%
- Kankakee33 prefixes, 4%
- Woodstock28 prefixes, 4%
- Dekalb24 prefixes, 3%
- Lockport18 prefixes, 2%
- Freeport18 prefixes, 2%
- McHenry18 prefixes, 2%
Also served: Crystal Lake, Sterling, Plainfield and Morris and 176 smaller places.
Frontier holds the most phone number prefixes in area code 815: 160 of 786.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 786 prefixes in use in 815 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| FrontierLandline company | 160 | 20% |
| Illinois Bell (AT&T)AT&T's landline company | 157 | 20% |
| Level 3 (Lumen)Lumen's business and wholesale network | 76 | 10% |
| Aero North Communications | 43 | 5% |
| AT&T MobilityMobile network | 42 | 5% |
| T-MobileMobile network | 40 | 5% |
| 39 other carriers | 268 | 34% |
66% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
815 has been overlaid once since 1947.
1947
815 is one of the original North American area codes.
2007
On March 17, 2007, 779 is added on top of 815, so new numbers here can get either code.
An 815 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 815 are 630, 847 and 708.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
These are the questions people ask most about area code 815.
Where is area code 815?
815 covers Rockford, Joliet, Kankakee and Woodstock and 184 more places in Illinois. In the 815 area, phone numbers are given out most in Will County, then Winnebago and McHenry counties.
What state is area code 815 in?
Illinois. 815 is an Illinois area code on Central Time.
What cities use area code 815?
The places holding the most 815 prefixes are Rockford, Joliet, Kankakee, Woodstock, Dekalb, Lockport, Freeport and McHenry, out of 188 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 815?
No single phone company owns 815. NANPA's records show Frontier holds the most 815 prefixes, 160 of 786, followed by Illinois Bell (AT&T) and Level 3 (Lumen). Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 815 in?
815 is on Central Time.
When did area code 815 start?
815 is one of the original North American area codes, in service since 1947.
Is 815 the same area as 779?
Yes. 779 (since 2007) covers the same ground as 815. Nobody's number changed when it was added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.
How do I dial an 815 number?
Local calls need 1, then the area code, then the number: 1-815-555-0142.
Is 815 a toll-free number?
No. 815 is a regular area code for Rockford and Joliet in Illinois, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 815?
The closest are 630/331 (Roselle, Illinois), 847/224 (Northbrook, Illinois), 708/464 (La Grange, Illinois) and 312/773/872 (Chicago, Illinois), measured between the centres of each area.
Who called me from an 815 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 815 a scam?
815 is a real Illinois area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.