Illinois · Central Time
872 Area Code
Area code 872 is in Illinois, serving the entire city of Chicago, overlaying both 312 (downtown) and 773 (the rest of the city). It is in the Central Time zone. It shares its territory with overlay codes 312 and 773, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 872 area code?
872 is a Illinois area code covering the entire city of Chicago, overlaying both 312 (downtown) and 773 (the rest of the city). In the wider directory it sits in the Midwest region.
Cities in the 872 area code
Counties served by 872
Cook County.
872 overlay codes and dialing
The 872 territory is covered by an overlay of 3 area codes: 312, 773, 872. All of them serve the same geographic area, and the original code is 312. 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 872 area code
872 went into service on November 7, 2009 as an overlay of 312, relieving number exhaustion in the Chicago area. Rather than splitting the region, the overlay lets existing customers keep their numbers while new lines draw from the added code. Learn more in our overlay guide.
Is 872 a scam or spam risk?
872 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 872 number on your screen is no guarantee the caller is in Chicago, 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
872 area code FAQ
Where is the 872 area code?
The 872 area code is in Illinois, covering the entire city of Chicago, overlaying both 312 (downtown) and 773 (the rest of the city), in the Midwest region.
What cities are in the 872 area code?
Cities in the 872 area code include Chicago.
What time zone is 872 in?
872 is in the Central Time zone.
What is the overlay for the 872 area code?
872 shares its territory with 312 and 773. All 3 codes (312, 773, 872) serve the same area, so 10-digit dialing is required for every call.
When did the 872 area code start?
872 went into service on November 7, 2009 as an overlay of 312.
Do I have to dial 10 digits for 872?
Yes. Because 872 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 872 a toll-free or premium code?
No. 872 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.