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US area code · Illinois

Area code 331

Where the 331 area code is, its overlay and how to dial a +1 331 number from anywhere.

CoversAddison, IllinoisTime zoneCentral (CT)TypeOverlay
Quick answer

The 331 area code is in Addison, Illinois, United States (Central (CT)). To call from abroad: +1 331 555-0123. It is an overlay, so all 10 digits are dialled.

StateIllinois
Main areaAddison
Time zoneCentral (CT)
TypeOverlay
10-digit dialingRequired
In service since23-Jul-1999

The 331 area code is a geographic North American Numbering Plan (NANP) code covering Addison, Illinois. It has been in service since 23-Jul-1999 and sits in the Central (CT) time zone.

Overlay 331 shares its region

Several area codes cover the same geographic area, so two neighbours can have different codes. Because of the overlay, you must dial all 10 digits (area code + number) even for local calls.

331630

How to dial a 331 number

From abroad+1 331 555-0123
Within the US / Canada1 331 555-0123
Locally (same area)331 555-0123

Cities in the 331 area code

A 331 number is usually in one of these places in Illinois — 5 counties.

Addison DupageBartlett DupageBatavia KaneBensenville DupageBloomingdale DupageBolingbrook WillCarol Stream DupageDarien DupageDowners Grove DupageElmhurst DupageGlen Ellyn DupageGlendale Heights DupageHanover Park CookLisle DupageLombard DupageNaperville Dupage;WillNorth Aurora KaneRoselle DupageSaint Charles KaneStreamwood CookVilla Park DupageWest Chicago DupageWestmont DupageWheaton DupageWoodridge Dupage

Other Illinois area codes

217224309312447464618630708730773779815847861872

Frequently asked questions

Where is the 331 area code?

The 331 area code is in Addison, Illinois, United States (Central (CT)).

Is 331 an overlay area code?

Yes. 331 overlays the same region as 630, so callers dial all 10 digits.

Do I have to dial 10 digits for 331?

Yes — dial the area code plus the seven-digit number.

How do I call a 331 number from another country?

Dial your exit code (or +), then 1, then 331, then the number: +1 331 555-0123.

Source: NANPA numbering plan. An area code covers a region, not a precise address — a 331 number does not pinpoint a street or ZIP code.

Missed a call from +1 331?

In the 30 days to September 24, 2026, 313 unwanted calls showing a 331 number were reported to the US Federal Trade Commission, 61% of them recorded messages or robocalls. That puts 331 at #281 of 670 area codes reported.

Other109
Reducing your debt (credit cards, mortgage, student loans)98
Dropped call or no message30
Calls pretending to be government, businesses, or family and friends23
Before you call back
  • If you do not know anyone in Illinois, do not call back: a genuine caller will leave a message or send a text.
  • Scammers fake the number shown on caller ID, so a 331 number can hide a caller anywhere in the world.
  • Never give a code received by text or a bank detail to an unknown caller. In the US, calls can be reported at reportfraud.ftc.gov.

Who issues +1 331 numbers

Phone companies hold blocks of numbers in each area code. The main holders in 331:

T-Mobile USA, Inc. 42Onvoy, LLC 39Cellco Partnership Dba Verizon Wireless 33New Cingular Wireless PCS, LLC 26Fractel, LLC 18Bandwidth.Com CLEC, LLC 11

About 42.3% of the 239 prefixes in use belong to mobile carriers: a 331 number is often a cell phone, and it may have moved to another carrier since.

Sources: FTC Do Not Call reported calls (numbers as reported by consumers, not verified), NANPA central office code assignments.

All US area codes United States +1 Map of area code 331 — cities & rate centres