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
West Chicago	(331) 240 , (331) 465
Lombard	(331) 462 , (331) 551
Hanover Park	(331) 200 , (331) 245
Montgomery	(331) 330

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%
T Mobile Usa Inc	Wireless	10%
Denali Spectrum License Llc	Wireless	10%
Cygnus Telecommunications Corporation Il	Landline	6%
New Cingular Wireless Pcs Llc Il	Wireless	6%
Level 3 Communications Llc Il	Landline	4%
Peerless Network Of Illinois Llc Il	Landline	4%
Bandwidth Com Clec Llc Il	Wireless	3%
Ameritech Illinois	Landline	3%
Comcast Phone Of Illinois Llc Dba Comco Il	Landline	1%
Sigecom Llc Il	Landline	1%
Cibolo Creek Ventures Llc Dba Routepoint Comm Il		1%
Xo Illinois Inc	Landline	1%
Digital Network Access Communications Inc Il	Landline	1%
Mci Worldcom Communications Inc Il	Landline	1%
Ovation Communications Of Illinois Inc	Wireless	1%
Local Access Llc	Landline	1%
Globalcom Inc Il	Landline	1%

Prefixes

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