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331 Area CodeAurora, IL

Area code 331 covers Aurora and 60 other cities in Illinois: 1,703,350 people in 5 counties, led by DuPage and Kane, on Central Time (CT). It overlays 630.

Overview

Major City
Aurora
State
Illinois (IL)
Timezone
Central Time (CT)
Current Time
–:––
Overlay
Yes – shares area with 630

Nearby Area Codes

Where is area code 331?

Overview of the 331 Area Code

Geographic Coverage of the 331 Area Code

All 61 cities

Aurora Area Codes Overview

What cities does area code 331 cover?

CityStatePopulationPopulation in 331% of listed-city population% of City
AuroraIL180,710180,71010.6%100.0%
NapervilleIL153,124148,9189.0%97.3%
JolietIL151,83708.9%0.0%
BolingbrookIL74,75668,2884.4%91.3%
WheatonIL53,74153,7413.2%100.0%
Downers GroveIL50,55250,5523.0%100.0%
PlainfieldIL48,8816,9852.9%14.3%
ElmhurstIL46,10846,1082.7%100.0%
LombardIL44,49044,4902.6%100.0%
RomeovilleIL41,1774,6102.4%11.2%
BartlettIL40,71836,4522.4%89.5%
Carol StreamIL39,55639,5562.3%100.0%
OswegoIL38,77838,7782.3%100.0%
StreamwoodIL38,36034,9352.3%91.1%
Hanover ParkIL36,68536,6852.2%100.0%
AddisonIL35,72835,7282.1%100.0%
WoodridgeIL34,10334,1032.0%100.0%
St. CharlesIL33,48233,4822.0%100.0%
Glendale HeightsIL32,86632,8661.9%100.0%
Glen EllynIL28,87228,8721.7%100.0%
BataviaIL26,55526,5551.6%100.0%
YorkvilleIL25,98625,9861.5%100.0%
West ChicagoIL25,46925,4691.5%100.0%
WestmontIL24,30824,3081.4%100.0%
LisleIL23,54823,5481.4%100.0%
RoselleIL22,87122,8711.3%100.0%
BloomingdaleIL22,62222,6221.3%100.0%
Villa ParkIL22,02022,0201.3%100.0%
DarienIL22,01522,0151.3%100.0%
MontgomeryIL21,95721,9571.3%100.0%
GenevaIL21,16821,1681.2%100.0%
North AuroraIL19,32919,3291.1%100.0%
BensenvilleIL18,62918,6291.1%100.0%
LemontIL18,20318,2031.1%100.0%
HinsdaleIL17,59817,5981.0%100.0%
WarrenvilleIL15,24715,2470.9%100.0%
Wood DaleIL13,98313,9830.8%100.0%
PlanoIL12,67712,6770.7%100.0%
Burr RidgeIL11,20211,2020.7%100.0%
Campton HillsIL10,89410,8940.6%100.0%
WinfieldIL10,19910,1990.6%100.0%
ItascaIL9,5069,5060.6%100.0%
Sugar GroveIL9,3399,3390.5%100.0%
WillowbrookIL9,1799,1790.5%100.0%
Clarendon HillsIL8,7038,7030.5%100.0%
Oak BrookIL8,1888,1880.5%100.0%
Boulder HillIL8,1088,1080.5%100.0%
SandwichIL7,29900.4%0.0%
ElburnIL6,8266,8260.4%100.0%
Willow SpringsIL5,79300.3%0.0%
Palos ParkIL4,8102,9080.3%60.5%
Indian Head ParkIL3,95600.2%0.0%
Oakbrook TerraceIL2,7292,7290.2%100.0%
WayneIL2,2852,2850.1%100.0%
PrestburyIL1,7221,7220.1%100.0%
Maple ParkIL1,48200.1%0.0%
Big RockIL1,0861,0860.1%100.0%
Lily LakeIL1,0591,0590.1%100.0%
KanevilleIL4474470.0%100.0%
VirgilIL2842840.0%100.0%
MillbrookIL28200.0%0.0%

City population is shown in full; each city's share inside 331 is measured from Census tract centroids.

What counties does area code 331 cover?

CountyStatePopulation in 331% of area-code footprint% of County
DuPage CountyIL932,87755%100%
Kane CountyIL293,03417%57%
Cook CountyIL224,23113%4%
Will CountyIL141,2788%20%
Kendall CountyIL111,9307%85%
Sources:

Has area code 331 been reported for unwanted calls?

Yes – 1,638 FTC complaints, May 29 – Oct 1, 2026.

  • 70% robocalls
  • ↓ 20% vs prior period
  • FTC data, retrieved 2026-10-05

Most-reported subjects

  • Reducing your debt (credit cards, mortgage, student loans)40%648
  • Other34%561
  • Calls pretending to be government, businesses, or family and friends8%138

Caller ID is easily spoofed, so these figures reflect the number shown on caller ID, not the caller's true location – an area code alone never identifies a caller. The FTC does not verify the facts in these complaints.

Which prefixes and exchanges belong to area code 331?

19% assigned to a telco

  • 52% Landline
  • 48% Wireless
  • 0% Unknown
PrefixUsageCarrier
(331)200-WirelessT-Mobile Usa
(331)201-WirelessVerizon Wireless
(331)202-WirelessSprint Spectrum
(331)203-WirelessSprint Spectrum
(331)204-LandlineOnvoy
(331)205-WirelessT-Mobile Usa
(331)206-WirelessSprint Spectrum
(331)207-LandlineLevel 3 Communications
(331)208-WirelessSprint Spectrum
(331)209-LandlineLevel 3 Communications
(331)210-LandlinePeerless Network Of Illinois
(331)212-LandlineMcimetro Access Transmission Services
(331)213-WirelessVerizon Wireless
(331)214-WirelessVerizon Wireless
(331)215-WirelessVerizon Wireless
(331)216-WirelessNew Cingular Wireless Pcs
(331)218-WirelessT-Mobile Usa
(331)219-LandlineTelnyx
(331)220-WirelessSprint Spectrum
(331)221-LandlineIllinois Bell Tel Co
(331)222-WirelessNew Cingular Wireless Pcs
(331)223-WirelessNew Cingular Wireless Pcs
(331)225-WirelessSprint Spectrum
(331)226-WirelessT-Mobile Usa
(331)227-WirelessVerizon Wireless
(331)228-LandlineOvation Communications Of Illinois
(331)229-WirelessVerizon Wireless
(331)230-WirelessT-Mobile Usa
(331)231-WirelessNew Cingular Wireless Pcs
(331)232-WirelessNew Cingular Wireless Pcs
(331)233-LandlineTelnyx
(331)234-WirelessVerizon Wireless
(331)235-WirelessNew Cingular Wireless Pcs
(331)236-WirelessT-Mobile Usa
(331)237-LandlineMcimetro Access Transmission Services
(331)238-LandlineTeleport Communications America
(331)239-LandlineOnvoy
(331)240-LandlinePeerless Network Of Illinois
(331)241-LandlineOnvoy
(331)242-WirelessT-Mobile Usa
(331)243-WirelessT-Mobile Usa
(331)244-LandlineOnvoy
(331)245-WirelessT-Mobile Usa
(331)246-WirelessT-Mobile Usa
(331)247-LandlineVonage America
(331)248-LandlineComcast Ip Phone
(331)249-LandlineOnvoy
(331)250-WirelessT-Mobile Usa
(331)251-WirelessVerizon Wireless
(331)252-LandlineTeleport Communications America
(331)253-WirelessT-Mobile Usa
(331)254-WirelessT-Mobile Usa
(331)255-LandlineOnvoy
(331)256-WirelessVerizon Wireless
(331)257-WirelessNew Cingular Wireless Pcs
(331)258-LandlineOnvoy
(331)259-LandlinePeerless Network Of Illinois
(331)260-LandlineTeleport Communications America
(331)261-WirelessT-Mobile Usa
(331)262-WirelessSprint Spectrum
(331)263-LandlineOnvoy
(331)264-LandlineLevel 3 Communications
(331)265-LandlineOnvoy
(331)266-WirelessNew Cingular Wireless Pcs
(331)267-LandlineVonage America
(331)268-WirelessT-Mobile Usa
(331)269-WirelessT-Mobile Usa
(331)270-LandlineOnvoy
(331)271-LandlineOnvoy
(331)272-LandlineOnvoy
(331)273-LandlineOnvoy
(331)274-WirelessT-Mobile Usa
(331)275-WirelessT-Mobile Usa
(331)276-WirelessVerizon Wireless
(331)277-WirelessNew Cingular Wireless Pcs
(331)278-WirelessNew Cingular Wireless Pcs
(331)279-LandlinePaetec Communications
(331)280-WirelessVerizon Wireless
(331)281-LandlineIllinois Bell Tel Co
(331)282-LandlineOnvoy
(331)283-WirelessT-Mobile Usa
(331)284-WirelessT-Mobile Usa
(331)285-WirelessVerizon Wireless
(331)286-WirelessVerizon Wireless
(331)287-LandlineBandwidth.Com Clec
(331)288-LandlineTon80 Communications
(331)289-WirelessT-Mobile Usa
(331)290-WirelessVerizon Wireless
(331)291-WirelessVerizon Wireless
(331)292-LandlineOnvoy Spectrum
(331)293-WirelessNew Cingular Wireless Pcs
(331)294-WirelessVerizon Wireless
(331)295-LandlineNuso
(331)299-LandlineFractel
(331)300-WirelessT-Mobile Usa
(331)301-LandlineMetropcs
(331)302-WirelessVerizon Wireless
(331)303-LandlineBandwidth.Com Clec
(331)304-WirelessT-Mobile Usa
(331)305-WirelessVerizon Wireless
(331)307-WirelessT-Mobile Usa
(331)308-LandlineBandwidth.Com Clec
(331)310-LandlineBandwidth.Com Clec
(331)313-LandlineOnvoy Spectrum
(331)315-WirelessNew Cingular Wireless Pcs
(331)318-LandlineBandwidth.Com Clec
(331)321-WirelessT-Mobile Usa
(331)330-WirelessNew Cingular Wireless Pcs
(331)332-WirelessNew Cingular Wireless Pcs
(331)333-WirelessNew Cingular Wireless Pcs
(331)334-LandlineOnvoy
(331)336-LandlineFractel
(331)341-LandlineRadiantiq
(331)343-LandlineOnvoy
(331)345-LandlineFractel
(331)348-LandlineFractel
(331)356-LandlineFractel
(331)373-LandlineTon80 Communications
(331)385-WirelessNew Cingular Wireless Pcs
(331)388-LandlineFractel
(331)399-LandlineFractel
(331)400-LandlineFractel
(331)401-LandlineLevel 3 Communications
(331)422-LandlineLevel 3 Communications
(331)425-WirelessT-Mobile Usa
(331)426-LandlineTon80 Communications
(331)431-LandlineBandwidth.Com Clec
(331)442-WirelessVerizon Wireless
(331)444-WirelessVerizon Wireless
(331)452-WirelessVerizon Wireless
(331)454-WirelessNew Cingular Wireless Pcs
(331)456-LandlineFirst Communications
(331)457-WirelessVerizon Wireless
(331)462-LandlineXo Illinois
(331)465-WirelessNew Cingular Wireless Pcs
(331)466-LandlineTon80 Communications
(331)472-WirelessT-Mobile Usa
(331)481-WirelessVerizon Wireless
(331)500-LandlineFractel
(331)529-LandlineFractel
(331)551-WirelessNew Cingular Wireless Pcs
(331)575-WirelessSprint Spectrum
(331)588-WirelessNew Cingular Wireless Pcs
(331)600-LandlineFractel
(331)625-WirelessVerizon Wireless
(331)627-LandlineTon80 Communications
(331)631-LandlineOnvoy Spectrum
(331)642-LandlineBandwidth.Com Clec
(331)643-WirelessSprint Spectrum
(331)645-WirelessSprint Spectrum
(331)666-LandlineOnvoy
(331)684-LandlineRcn Telecom Services Of Illinios
(331)688-LandlineTon80 Communications
(331)701-WirelessVerizon Wireless
(331)702-LandlineMcimetro Access Transmission Services
(331)703-WirelessT-Mobile Usa
(331)704-LandlineBandwidth.Com Clec
(331)707-WirelessT-Mobile Usa
(331)716-LandlineOnvoy
(331)717-WirelessNew Cingular Wireless Pcs
(331)725-WirelessNew Cingular Wireless Pcs
(331)732-LandlineFractel
(331)746-LandlineTon80 Communications
(331)757-WirelessT-Mobile Usa
(331)758-LandlineFractel
(331)771-LandlineOnvoy
(331)775-LandlineComcast Ip Phone
(331)777-WirelessVerizon Wireless
(331)788-LandlineFractel
(331)800-LandlineOnvoy
(331)801-LandlineTeleport Communications America
(331)803-LandlinePeerless Network Of Illinois
(331)806-LandlineComcast Ip Phone
(331)808-LandlineBandwidth.Com Clec
(331)814-WirelessT-Mobile Usa
(331)825-LandlineDigital Network Access Communications
(331)826-WirelessSprint Spectrum
(331)837-LandlineTon80 Communications
(331)850-LandlineRadiantiq
(331)866-LandlineTon80 Communications
(331)867-LandlineFractel
(331)871-LandlineOnvoy
(331)888-LandlinePeerless Network Of Illinois
(331)899-LandlineFractel
(331)900-LandlineFractel
(331)901-LandlineBandwidth.Com Clec
(331)903-LandlineAt&T
(331)946-LandlineFractel
(331)979-LandlineComcast Ip Phone
(331)980-WirelessT-Mobile Usa
(331)998-WirelessVerizon Wireless
(331)999-LandlineBandwidth.Com Clec

Frequently Asked Questions about the 331 Area Code

Who called me from a 331 number?

48% of its assigned prefixes are wireless. Largest holders: T-Mobile Usa, Verizon Wireless, and New Cingular Wireless Pcs.

Is 331 a scam area code?

Carriers hold 19% of its possible prefixes.

Why do I keep getting calls from the 331 area code?

Complaints fell 20% on the prior period.

Should I answer an unknown 331 number?

70% of its FTC complaints were robocalls. Its most-reported subject was "Reducing your debt (credit cards, mortgage, student loans)", at 40%.

How do I block calls from the 331 area code?

Blocking 331 still lets 630 numbers through.

Where is area code 331?

331 covers 61 cities and 1,703,350 residents in 5 Illinois counties, led by DuPage, Kane, and Cook.

When did area code 331 go into service?

331 went into service on October 7, 2007. It was added to overlay 630.

Is 331 a real area code?

Yes: 27 carriers hold its prefixes, serving 61 cities in DuPage, Kane, Cook, and 2 other counties.

What timezone is the 331 area code in?

331 is on Central Time (CT).

How do I call a 331 number from abroad?

Dial +1 331, then the number.

Related Area Codes