What time zone is area code 331 in?

Area code 331 uses Central Time.

What area codes overlay 331?

630 serves the same area as 331. New numbers in the area can get any of these codes, which is why local calls need all 10 digits.

Is a call from area code 331 a scam?

The area code alone doesn’t tell you. Most calls from 331 are ordinary local calls, but scammers can fake (“spoof”) any number. If you don’t recognize a 331 number, let it go to voicemail.

When did area code 331 start?

331 went into service in 2007. It was created from area code 630.

Can a 331 number be outside Illinois?

Yes. People keep their numbers when they move and when they switch to mobile or internet phone services, so a 331 caller can be anywhere.

Area code 331

Where is area code 331?

Aurora, Naperville and Downers Grove, Illinois

Local time: … (Central Time)

State	Illinois
Country	United States
Main cities	Aurora, Naperville and Downers Grove
Time zone	Central Time
Overlay area codes	630
In service since	2007 (created from 630)
Assigned prefixes	224
Dialing format	(331) XXX-XXXX · +1 331 XXX XXXX from abroad

Look up a 331 number

Cities and towns in area code 331

Listed by how many phone prefixes (the 3 digits after the area code) are assigned to each place in 331.

Phone companies in area code 331

The carriers that hold the most 331 prefixes. People can move their number to another carrier, so this shows who first issued a number, not who serves it today.

Prefixes	Carrier
42	T-Mobile USA
39	Onvoy
33	Verizon Wireless
26	New Cingular Wireless PCS (AT&T)
18	Fractel
11	Bandwidth.com CLEC
9	Ton80 Communications
6	Level 3 Communications

All 224 prefixes in area code 331

Pick the 3 digits after the area code to see that prefix’s city and carrier.

Area codes that overlay 331

Questions

Where is area code 331?: Area code 331 is in Illinois. It serves Aurora, Naperville, Downers Grove, St. Charles and Lombard and 19 other cities and towns.
What time zone is area code 331 in?: Area code 331 uses Central Time.
What area codes overlay 331?: 630 serves the same area as 331. New numbers in the area can get any of these codes, which is why local calls need all 10 digits.
Is a call from area code 331 a scam?: The area code alone doesn’t tell you. Most calls from 331 are ordinary local calls, but scammers can fake (“spoof”) any number. If you don’t recognize a 331 number, let it go to voicemail.
When did area code 331 start?: 331 went into service in 2007. It was created from area code 630.
Can a 331 number be outside Illinois?: Yes. People keep their numbers when they move and when they switch to mobile or internet phone services, so a 331 caller can be anywhere.

Other area codes in Illinois

Area code	Main cities
217	Springfield, Champaign and Decatur
224	Northbrook, Arlington Hts and Des Plaines
309	Peoria, Bloomington and Rock Island
312	Chicgozn01, Wheeling and Oak Brook
447	Danville, Springfield and Champaign
464	Oak For So, Forest Park and La Grange
618	Collinsville, Carbondale and Belleville
708	La Grange, Chicago Heights and Oak Forest
730	Centralia, Herrin and Belleville
773	Harwood Heights, Chicgozn01 and Chicgozn02
779	Rockford, Joliet and Momence
815	Rockford, Joliet and Kankakee
847	Northbrook, Schaumburg and Arlington Hts
861	Peoria, Danvers and Moline
872	Chicgozn01, Harwood Heights and Chicgozn04