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
Geneva	(331) 210 , (331) 222 , (331) 223 , (331) 228 , (331) 248 , (331) 422 , (331) 442 , (331) 588 , (331) 825
Naperville	(331) 213 , (331) 215 , (331) 229 , (331) 281 , (331) 332 , (331) 333 , (331) 444 , (331) 457 , (331) 472
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
Hanover Park	(331) 200 , (331) 245
Lombard	(331) 462 , (331) 551
Yorkville	(331) 207

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

Prefixes

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