331 Area Code in Illinois, United States

Description

Area code 331 is an overlay for area code 630, serving the western suburbs of Chicago, including cities such as Naperville, Aurora, Wheaton, and Downers Grove. It was introduced in 2007 to address number exhaustion in the rapidly growing suburban corridor west of the city. The 331/630 region is known for its mix of residential communities, corporate headquarters, and educational institutions. Ten-digit dialing is required throughout the area. While 630 retains historical significance, 331 has become increasingly common on mobile and business lines. The dual-code area continues to be one of the most dynamic and affluent regions in Illinois.

Time & Time Zone

Time zone:

Central (GMT -06:00)

Current time:

Map

Major Cities

City	Prefixes
Aurora	(331) 203 , (331) 205 , (331) 206 , (331) 208 , (331) 212 , (331) 220 , (331) 250 , (331) 256 , (331) 262 , (331) 301 , (331) 302 , (331) 425 , (331) 431 , (331) 452 , (331) 454 , (331) 575 , (331) 643 , (331) 684
Naperville	(331) 213 , (331) 215 , (331) 229 , (331) 281 , (331) 332 , (331) 333 , (331) 444 , (331) 457 , (331) 472
Geneva	(331) 210 , (331) 222 , (331) 223 , (331) 228 , (331) 248 , (331) 422 , (331) 442 , (331) 588 , (331) 825
Elmhurst	(331) 202 , (331) 209 , (331) 221 , (331) 225 , (331) 591 , (331) 642 , (331) 645 , (331) 826
Downers Grove	(331) 201 , (331) 214 , (331) 251 , (331) 481 , (331) 625 , (331) 777
Oswego	(331) 216 , (331) 725 , (331) 999
Kane	(331) 227 , (331) 234 , (331) 303
Dupage	(331) 218 , (331) 552 , (331) 553
Lombard	(331) 462 , (331) 551
Hanover Park	(331) 200 , (331) 245
West Chicago	(331) 240 , (331) 465
Warrenville	(331) 888

Counties

County	Prefixes
Dupage	(331) 201 , (331) 202 , (331) 209 , (331) 213 , (331) 214 , (331) 215 , (331) 218 , (331) 221 , (331) 225 , (331) 229 , (331) 240 , (331) 251 , (331) 281 , (331) 332 , (331) 333 , (331) 444 , (331) 456 , (331) 457 , (331) 462 , (331) 465 , (331) 472 , (331) 481 , (331) 551 , (331) 552 , (331) 553 , (331) 591 , (331) 625 , (331) 642 , (331) 645 , (331) 777 , (331) 826 , (331) 888
Kane	(331) 203 , (331) 205 , (331) 206 , (331) 208 , (331) 210 , (331) 212 , (331) 220 , (331) 222 , (331) 223 , (331) 227 , (331) 228 , (331) 234 , (331) 248 , (331) 250 , (331) 256 , (331) 262 , (331) 301 , (331) 302 , (331) 303 , (331) 422 , (331) 425 , (331) 431 , (331) 442 , (331) 452 , (331) 454 , (331) 575 , (331) 588 , (331) 643 , (331) 684 , (331) 825
Kendall	(331) 207 , (331) 216 , (331) 330 , (331) 725 , (331) 999
Cook	(331) 200 , (331) 245
Will	(331) 803

Telephone Carriers

Carrier	Type	Prefixes (%)
Cellco Partnership Dba Verizon Wireless Il	Wireless	20%
Sprint Spectrum L P	Wireless	16%
Denali Spectrum License Llc	Landline	10%
T Mobile Usa Inc	Wireless	10%
New Cingular Wireless Pcs Llc Il	Wireless	6%
Cygnus Telecommunications Corporation Il	Landline	6%
Peerless Network Of Illinois Llc Il	Landline	4%
Level 3 Communications Llc Il	Landline	4%
Ameritech Illinois	Landline	3%
Bandwidth Com Clec Llc Il	Wireless	3%
Local Access Llc	Landline	1%
Xo Illinois Inc	Landline	1%
Sigecom Llc Il	Landline	1%
Cibolo Creek Ventures Llc Dba Routepoint Comm Il		1%
Digital Network Access Communications Inc Il	Landline	1%
Ovation Communications Of Illinois Inc	Wireless	1%
Comcast Phone Of Illinois Llc Dba Comco Il	Landline	1%
Globalcom Inc Il	Landline	1%
Mci Worldcom Communications Inc Il	Landline	1%

Prefixes

Prefix	City	Carrier	Type
(331) 202	Elmhurst	Sprint Spectrum L.p.	Wireless
(331) 431	Aurora	Bandwidth.com Clec, Llc - Il	Wireless
(331) 472	Naperville	T-mobile Usa, Inc.	Wireless
(331) 777	Downers Grove	Cygnus Telecommunications Corporation - Il	Landline
(331) 245	Hanover Park	T-mobile Usa, Inc.	Wireless
(331) 330	Montgomery	Denali Spectrum License, Llc	Landline
(331) 216	Oswego	New Cingular Wireless Pcs, Llc - Il	Wireless
(331) 591	Elmhurst		Wireless
(331) 553	Dupage
(331) 218	Dupage	T-mobile Usa, Inc.
(331) 229	Naperville	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 444	Naperville	Cygnus Telecommunications Corporation - Il	Landline
(331) 250	Aurora	T-mobile Usa, Inc.	Wireless
(331) 825	Geneva	Digital Network Access Communications, Inc. - Il	Landline
(331) 222	Geneva	Denali Spectrum License, Llc	Wireless
(331) 205	Aurora	T-mobile Usa, Inc.	Wireless
(331) 457	Naperville	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 452	Aurora	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 588	Geneva	New Cingular Wireless Pcs, Llc - Il	Wireless
(331) 206	Aurora	Sprint Spectrum L.p.	Wireless
(331) 456	Roselle	Globalcom, Inc.-il	Landline
(331) 227	Kane
(331) 240	West Chicago	Peerless Network of Illinois, Llc - Il	Landline
(331) 223	Geneva	Denali Spectrum License, Llc	Wireless
(331) 207	Yorkville	Level 3 Communications, Llc - Il	Landline
(331) 803	Homer Glen	Peerless Network of Illinois, Llc - Il	Landline
(331) 645	Elmhurst	Sprint Spectrum L.p.	Wireless
(331) 256	Aurora	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 302	Aurora	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 826	Elmhurst	Sprint Spectrum L.p.	Wireless
(331) 214	Downers Grove	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 454	Aurora	Denali Spectrum License, Llc	Wireless
(331) 221	Elmhurst	Ameritech Illinois	Landline
(331) 301	Aurora	Local Access Llc	Landline
(331) 888	Warrenville	Cygnus Telecommunications Corporation - Il	Landline
(331) 643	Aurora	Sprint Spectrum L.p.	Wireless
(331) 212	Aurora	Mci Worldcom Communications, Inc. - Il	Landline
(331) 462	Lombard	Xo Illinois, Inc.	Landline
(331) 551	Lombard	Denali Spectrum License, Llc	Wireless
(331) 225	Elmhurst	Sprint Spectrum L.p.	Wireless
(331) 684	Aurora	Sigecom, Llc - Il	Landline
(331) 201	Downers Grove	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 213	Naperville	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 200	Hanover Park	T-mobile Usa, Inc.	Wireless
(331) 642	Elmhurst	Bandwidth.com Clec, Llc - Il	Wireless
(331) 999	Oswego	Cygnus Telecommunications Corporation - Il	Landline
(331) 303	Kane	Cibolo Creek Ventures, Llc Dba Routepoint Comm Il
(331) 442	Geneva	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 234	Kane	Cellco Partnership Dba Verizon Wireless - Il
(331) 625	Downers Grove	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 208	Aurora	Sprint Spectrum L.p.	Wireless
(331) 333	Naperville	Denali Spectrum License, Llc	Wireless
(331) 215	Naperville	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 422	Geneva	Level 3 Communications, Llc - Il	Landline
(331) 262	Aurora	Sprint Spectrum L.p.	Wireless
(331) 281	Naperville	Ameritech Illinois	Landline
(331) 210	Geneva	Peerless Network of Illinois, Llc - Il	Landline
(331) 552	Dupage
(331) 575	Aurora	Sprint Spectrum L.p.	Wireless
(331) 725	Oswego	New Cingular Wireless Pcs, Llc - Il	Landline
(331) 203	Aurora	Sprint Spectrum L.p.	Wireless
(331) 481	Downers Grove	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 228	Geneva	Ovation Communications of Illinois, Inc.	Wireless
(331) 220	Aurora	Sprint Spectrum L.p.	Wireless
(331) 425	Aurora	T-mobile Usa, Inc.	Wireless
(331) 465	West Chicago	New Cingular Wireless Pcs, Llc - Il	Wireless
(331) 248	Geneva	Comcast Phone of Illinois, Llc Dba Comco - Il	Landline
(331) 251	Downers Grove	Cellco Partnership Dba Verizon Wireless - Il	Wireless
(331) 332	Naperville	Denali Spectrum License, Llc	Wireless
(331) 209	Elmhurst	Level 3 Communications, Llc - Il	Wireless