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331 Area Code — Scam Calls, Location & Who's Calling

Area code 331 serves Illinois in the Central time zone, in service since 2007. The FCC has 847 unwanted-call complaints against 595 different 331 numbers on record. Look up the exact number that called you below.

Most-reported 331 numbers

Ranked by FCC unwanted-call complaints. Click a number for its full report.

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.

Carriers operating in 331

Carriers assigned to 331 prefixes that visitors have looked up so far — resolved from official NPA-NXX assignment records.

  • CELLCO PARTNERSHIP DBA VERIZON WIRELESS - ILWireless · 7 prefixes
  • NEW CINGULAR WIRELESS PCS, LLC - ILWireless · 4 prefixes
  • T-MOBILE USA, INC.Wireless · 4 prefixes
  • PEERLESS NETWORK OF ILLINOIS, LLC - ILC · 2 prefixes
  • MCIMETRO ACCESS TRANSMISSION SERVICES LLC - ILC · 2 prefixes
  • NUSO, LLCC · 1 prefix
  • ONVOY SPECTRUM, LLCWireless · 1 prefix
  • ONVOY, LLCC · 1 prefix

About area code 331

Serves
Illinois
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 Illinois — 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 Illinois, 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 Illinois 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 847 unwanted-call complaints against 595 distinct 331 numbers in our current data window. Check the specific number's report page before returning a missed call.