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
Dupage	(331) 218 , (331) 552 , (331) 553
Kane	(331) 227 , (331) 234 , (331) 303
Hanover Park	(331) 200 , (331) 245
West Chicago	(331) 240 , (331) 465
Lombard	(331) 462 , (331) 551
Roselle	(331) 456

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

Prefixes

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