331 Area Code — IL
Area code 331 serves IL in the Central time zone, in service since 2007. The FCC has 27 unwanted-call complaints against 27 different 331 numbers on record. Look up the exact number that called you below.
Reported 331 numbers
No 331 numbers currently pass our complaint threshold. Look up the exact number that called you — the lookup works on every US number, whether or not it has complaint history.
331 unwanted-call complaints, last 12 months
Monthly FCC complaint volume against 331 numbers. Spikes usually mark an active robocall campaign cycling through the code.
About area code 331
- Serves
- IL
- Time zone
- Central
- In service since
- 2007-10-07
- Overlay
- Yes — 10-digit dialing
Source: NANPA numbering records, refreshed weekly.
Spam calls from 331? What to know
Seeing repeated missed calls from 331 numbers you don't recognize is the classic signature of neighbor-spoofing robocall campaigns. The caller isn't necessarily in IL — spoofing software displays whatever digits the campaign chooses. Never call unknown numbers back; look them up first, and report unwanted calls to the FCC to build the public record.
Area code 331 FAQs
Where is area code 331?
Area code 331 serves IL, in the Central time zone. It is part of an overlay complex, so multiple area codes serve the same territory and 10-digit dialing is required. It has been in service since 2007.
Why do I keep getting calls from 331 numbers?
Robocallers use "neighbor spoofing" — displaying a number with a local area code to make you more likely to answer. A call showing area code 331 may not originate from IL at all. Look up the full 10-digit number on this site to see its complaint history before calling back.
Are 331 numbers safe to call back?
Area codes themselves are neither safe nor unsafe — 331 contains millions of legitimate lines alongside any spoofed or spam numbers. The FCC has logged 27 unwanted-call complaints against 27 distinct 331 numbers in our current data window. Check the specific number's report page before returning a missed call.