Illinois · Central Time
618 Area Code
Area code 618 is in Illinois, serving southern Illinois, including the Metro East near St. Louis and Carbondale. It is in the Central Time zone. It shares its territory with overlay code 730, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 618 area code?
618 is a Illinois area code covering southern Illinois, including the Metro East near St. Louis and Carbondale. In the wider directory it sits in the Midwest region.
Cities in the 618 area code
- Belleville
- O'Fallon
- Granite City
- Edwardsville
- Collinsville
- Alton
- Carbondale
- Mount Vernon
- Marion
- Centralia
- East St. Louis
- Godfrey
Counties served by 618
St. Clair County, Madison County, Jackson County, Williamson County, Jefferson County, Marion County, Clinton County, Monroe County, Franklin County and Randolph County.
618 overlay codes and dialing
The 618 territory is covered by an overlay of 2 area codes: 618, 730. All of them serve the same geographic area, and the original code is 618. 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 618 area code
618 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 Belleville area ever since, with 730 later added as an overlay to supply more numbers.
Is 618 a scam or spam risk?
618 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 618 number on your screen is no guarantee the caller is in Belleville, 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 6XX 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
618 area code FAQ
Where is the 618 area code?
The 618 area code is in Illinois, covering southern Illinois, including the Metro East near St. Louis and Carbondale, in the Midwest region.
What cities are in the 618 area code?
Cities in the 618 area code include Belleville, O'Fallon, Granite City, Edwardsville, Collinsville, Alton, Carbondale, Mount Vernon, Marion and Centralia.
What time zone is 618 in?
618 is in the Central Time zone.
What is the overlay for the 618 area code?
618 shares its territory with 730. Both codes (618, 730) serve the same area, so 10-digit dialing is required for every call.
When did the 618 area code start?
618 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 618?
Yes. Because 618 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 618 a toll-free or premium code?
No. 618 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.