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US area code · Illinois

331 area code

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.

Number holders in area code 331

Each prefix (the three digits after the area code) is assigned by NANPA to one telephone company. 239 prefixes are in use in 331, shared by 27 companies. The largest holders:

CompanyPrefixesShare
T-Mobile USA, Inc.4218%
Onvoy, LLC3916%
Cellco Partnership Dba Verizon Wireless3314%
New Cingular Wireless PCS, LLC2611%
Fractel, LLC188%
Bandwidth.Com CLEC, LLC115%

Source: NANPA central office code assignments. A number keeps its original prefix when it is ported to another carrier.

Complaints about 331 numbers

Reports to the FTC, last 30 days
313
Recorded messages or robocalls
61%
Rank among area codes
#281 of 670
Most reported subjects
Other (109)
Reducing your debt (credit cards, mortgage, student loans) (98)
Dropped call or no message (30)

Period Aug 26 – Sep 24, 2026. These are the numbers shown on the caller ID of the reported calls; many are spoofed and do not belong to the real caller.

Source: US Federal Trade Commission, Do Not Call reported calls data (daily files).

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

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