Area Code Detail

Area Code 331

Illinois (Aurora, Naperville, Oswego; western suburbs of Chicago) · In service since October 7, 2007

IL
Reports, 30 Days 280

Recent FCC and FTC complaint records tied to this area code.

Reports, 180 Days 1,928

Broader complaint volume used to prioritize indexable pages.

Active Prefixes 239

Distinct NPA-NXX prefixes surfaced from routing and assignment data.

Carriers / Assignees 35

Named carriers, assignees, or code holders found in routing data.

Cities / Rate Centers 24

Distinct cities or rate centers attached to this area code.

States / Territories 1

Coverage footprint visible from NANPA, pooled block, and Canada routing data.

North American Phone Intelligence

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Paste raw digits, a formatted phone number, an area code, an NPA-NXX block, or a short code. US and Canada phone lookups route automatically, and international iMessage checks are available separately.

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Overview

What this area code covers

Illinois (Aurora, Naperville, Oswego; western suburbs of Chicago)

overlaid on 630

Common cities and rate centers

Aurora Bartlett Batavia Big Rock Downers Grove Elburn Elmhurst Geneva Glen Ellyn Hinsdale Itasca Kaneville Lemont Lombard Naperville Oswego Plano Roselle

Top carriers and assignees

  • ONVOY, LLC · 579 routing rows
  • T-MOBILE USA, INC. · 351 routing rows
  • NEW CINGULAR WIRELESS PCS, LLC - IL · 328 routing rows
  • CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL · 305 routing rows
  • BANDWIDTH.COM CLEC, LLC - IL · 176 routing rows
  • ONVOY SPECTRUM, LLC · 79 routing rows
  • PEERLESS NETWORK OF ILLINOIS, LLC - IL · 67 routing rows
  • COMCAST IP PHONE, LLC · 65 routing rows
  • LEVEL 3 COMMUNICATIONS, LLC - IL · 52 routing rows
  • FRACTEL, LLC · 52 routing rows
  • COMMIO, LLC · 48 routing rows
  • TELEPORT COMMUNICATIONS AMERICA, LLC - IL · 41 routing rows
NPA-NXX

Prefix directory inside area code 331

Each prefix below is collapsed to one primary locality row so you can scan the area code by prefix without the duplicated block-level assignment rows.

Prefix Primary Rate Center Primary City State
331-200-XXXX BARTLETT Bartlett IL
331-201-XXXX DOWNERSGRV Downers Grove IL
331-202-XXXX ELMHURST Elmhurst IL
331-203-XXXX AURORA Aurora IL
331-204-XXXX NAPERVILLE Naperville IL
331-205-XXXX AURORA Aurora IL
331-206-XXXX AURORA Aurora IL
331-207-XXXX YORKVILLE Yorkville IL
331-208-XXXX AURORA Aurora IL
331-209-XXXX ELMHURST Elmhurst IL
331-210-XXXX ST CHARLES Saint Charles IL
331-211-XXXX IL
331-212-XXXX AURORA Aurora IL
331-213-XXXX NAPERVILLE Naperville IL
331-214-XXXX DOWNERSGRV Downers Grove IL
331-215-XXXX NAPERVILLE Naperville IL
331-216-XXXX OSWEGO Oswego IL
331-217-XXXX LOMBARD Lombard IL
331-218-XXXX WHEATON Wheaton IL
331-219-XXXX AURORA Aurora IL
331-220-XXXX AURORA Aurora IL
331-221-XXXX ELMHURST Elmhurst IL
331-222-XXXX ST CHARLES Saint Charles IL
331-223-XXXX ST CHARLES Saint Charles IL
331-224-XXXX ITASCA Itasca IL
331-225-XXXX ELMHURST Elmhurst IL
331-226-XXXX NAPERVILLE Naperville IL
331-227-XXXX SUGARGROVE Sugar Grove IL
331-228-XXXX ST CHARLES Saint Charles IL
331-229-XXXX NAPERVILLE Naperville IL
331-230-XXXX AURORA Aurora IL
331-231-XXXX NAPERVILLE Naperville IL
331-232-XXXX W CHICAGO West Chicago IL
331-233-XXXX DOWNERSGRV Downers Grove IL
331-234-XXXX SUGARGROVE Sugar Grove IL
331-235-XXXX ST CHARLES Saint Charles IL
331-236-XXXX WHEATON Wheaton IL
331-237-XXXX NAPERVILLE Naperville IL
331-238-XXXX DOWNERSGRV Downers Grove IL
331-239-XXXX YORKVILLE Yorkville IL
331-240-XXXX W CHICAGO West Chicago IL
331-241-XXXX LOMBARD Lombard IL
331-242-XXXX LOMBARD Lombard IL
331-243-XXXX LOMBARD Lombard IL
331-244-XXXX NAPERVILLE Naperville IL
331-245-XXXX BARTLETT Bartlett IL
331-246-XXXX LEMONT Lemont IL
331-247-XXXX NAPERVILLE Naperville IL
331-248-XXXX GENEVA Geneva IL
331-249-XXXX NAPERVILLE Naperville IL
331-250-XXXX AURORA Aurora IL
331-251-XXXX DOWNERSGRV Downers Grove IL
331-252-XXXX WARRENVL Warrenville IL
331-253-XXXX LEMONT Lemont IL
331-254-XXXX SUGARGROVE Sugar Grove IL
331-255-XXXX AURORA Aurora IL
331-256-XXXX AURORA Aurora IL
331-257-XXXX AURORA Aurora IL
331-258-XXXX AURORA Aurora IL
331-259-XXXX SUGARGROVE Sugar Grove IL
331-260-XXXX DOWNERSGRV Downers Grove IL
331-261-XXXX LEMONT Lemont IL
331-262-XXXX AURORA Aurora IL
331-263-XXXX ITASCA Itasca IL
331-264-XXXX HINSDALE Hinsdale IL
331-265-XXXX GENEVA Geneva IL
331-266-XXXX ST CHARLES Saint Charles IL
331-267-XXXX LOMBARD Lombard IL
331-268-XXXX SUGARGROVE Sugar Grove IL
331-269-XXXX AURORA Aurora IL
331-270-XXXX AURORA Aurora IL
331-271-XXXX HINSDALE Hinsdale IL
331-272-XXXX ST CHARLES Saint Charles IL
331-273-XXXX LEMONT Lemont IL
331-274-XXXX AURORA Aurora IL
331-275-XXXX BARTLETT Bartlett IL
331-276-XXXX ST CHARLES Saint Charles IL
331-277-XXXX LOMBARD Lombard IL
331-278-XXXX AURORA Aurora IL
331-279-XXXX ELMHURST Elmhurst IL
331-280-XXXX DOWNERSGRV Downers Grove IL
331-281-XXXX NAPERVILLE Naperville IL
331-282-XXXX HINSDALE Hinsdale IL
331-283-XXXX GENEVA Geneva IL
331-284-XXXX BARTLETT Bartlett IL
331-285-XXXX NAPERVILLE Naperville IL
331-286-XXXX ST CHARLES Saint Charles IL
331-287-XXXX AURORA Aurora IL
331-288-XXXX ELBURN Elburn IL
331-289-XXXX HINSDALE Hinsdale IL
331-290-XXXX AURORA Aurora IL
331-291-XXXX DOWNERSGRV Downers Grove IL
331-292-XXXX DOWNERSGRV Downers Grove IL
331-293-XXXX AURORA Aurora IL
331-294-XXXX NAPERVILLE Naperville IL
331-295-XXXX AURORA Aurora IL
331-296-XXXX WHEATON Wheaton IL
331-297-XXXX BATAVIA Batavia IL
331-298-XXXX NAPERVILLE Naperville IL
331-299-XXXX HINSDALE Hinsdale IL
331-300-XXXX AURORA Aurora IL
331-301-XXXX AURORA Aurora IL
331-302-XXXX AURORA Aurora IL
331-303-XXXX ELBURN Elburn IL
331-304-XXXX BARTLETT Bartlett IL
331-305-XXXX NAPERVILLE Naperville IL
331-306-XXXX DOWNERSGRV Downers Grove IL
331-307-XXXX LOMBARD Lombard IL
331-308-XXXX BARTLETT Bartlett IL
331-309-XXXX LEMONT Lemont IL
331-310-XXXX BIG ROCK Big Rock IL
331-311-XXXX IL
331-312-XXXX AURORA Aurora IL
331-313-XXXX NAPERVILLE Naperville IL
331-314-XXXX ST CHARLES Saint Charles IL
331-315-XXXX LOMBARD Lombard IL
331-316-XXXX NAPERVILLE Naperville IL
331-317-XXXX HINSDALE Hinsdale IL
331-318-XXXX LEMONT Lemont IL
331-319-XXXX AURORA Aurora IL
331-320-XXXX BARTLETT Bartlett IL
331-321-XXXX AURORA Aurora IL
331-322-XXXX LOMBARD Lombard IL
331-323-XXXX GLEN ELLYN Glen Ellyn IL
331-324-XXXX YORKVILLE Yorkville IL
331-325-XXXX LEMONT Lemont IL
331-326-XXXX DOWNERSGRV Downers Grove IL
331-327-XXXX ST CHARLES Saint Charles IL
331-328-XXXX NAPERVILLE Naperville IL
331-329-XXXX AURORA Aurora IL
331-330-XXXX NAPERVILLE Naperville IL
331-331-XXXX AURORA Aurora IL
331-332-XXXX NAPERVILLE Naperville IL
331-333-XXXX NAPERVILLE Naperville IL
331-334-XXXX BATAVIA Batavia IL
331-335-XXXX ST CHARLES Saint Charles IL
331-336-XXXX AURORA Aurora IL
331-337-XXXX OSWEGO Oswego IL
331-338-XXXX AURORA Aurora IL
331-339-XXXX AURORA Aurora IL
331-340-XXXX ITASCA Itasca IL
331-341-XXXX PLANO Plano IL
331-342-XXXX NAPERVILLE Naperville IL
331-343-XXXX DOWNERSGRV Downers Grove IL
331-344-XXXX W CHICAGO West Chicago IL
331-345-XXXX NAPERVILLE Naperville IL
331-346-XXXX NAPERVILLE Naperville IL
331-347-XXXX WHEATON Wheaton IL
331-348-XXXX ELBURN Elburn IL
331-349-XXXX ST CHARLES Saint Charles IL
331-356-XXXX BARTLETT Bartlett IL
331-373-XXXX OSWEGO Oswego IL
331-385-XXXX AURORA Aurora IL
331-388-XXXX SUGARGROVE Sugar Grove IL
331-399-XXXX DOWNERSGRV Downers Grove IL
331-400-XXXX OSWEGO Oswego IL
331-401-XXXX NAPERVILLE Naperville IL
331-411-XXXX IL
331-422-XXXX ST CHARLES Saint Charles IL
331-425-XXXX AURORA Aurora IL
331-426-XXXX LEMONT Lemont IL
331-431-XXXX AURORA Aurora IL
331-442-XXXX ST CHARLES Saint Charles IL
331-444-XXXX NAPERVILLE Naperville IL
331-452-XXXX AURORA Aurora IL
331-454-XXXX AURORA Aurora IL
331-456-XXXX ROSELLE Roselle IL
331-457-XXXX NAPERVILLE Naperville IL
331-462-XXXX LOMBARD Lombard IL
331-465-XXXX W CHICAGO West Chicago IL
331-466-XXXX GLEN ELLYN Glen Ellyn IL
331-472-XXXX NAPERVILLE Naperville IL
331-481-XXXX DOWNERSGRV Downers Grove IL
331-500-XXXX GENEVA Geneva IL
331-511-XXXX IL
331-529-XXXX NAPERVILLE Naperville IL
331-551-XXXX LOMBARD Lombard IL
331-555-XXXX IL
331-575-XXXX AURORA Aurora IL
331-588-XXXX ST CHARLES Saint Charles IL
331-591-XXXX IL
331-600-XXXX WHEATON Wheaton IL
331-611-XXXX IL
331-625-XXXX DOWNERSGRV Downers Grove IL
331-627-XXXX LOMBARD Lombard IL
331-631-XXXX DOWNERSGRV Downers Grove IL
331-642-XXXX ELMHURST Elmhurst IL
331-643-XXXX AURORA Aurora IL
331-645-XXXX ELMHURST Elmhurst IL
331-666-XXXX AURORA Aurora IL
331-684-XXXX AURORA Aurora IL
331-688-XXXX NAPERVILLE Naperville IL
331-700-XXXX IL
331-701-XXXX NAPERVILLE Naperville IL
331-702-XXXX NAPERVILLE Naperville IL
331-703-XXXX W CHICAGO West Chicago IL
331-704-XXXX KANEVILLE Kaneville IL
331-707-XXXX AURORA Aurora IL
331-711-XXXX IL
331-716-XXXX WHEATON Wheaton IL
331-717-XXXX OSWEGO Oswego IL
331-725-XXXX OSWEGO Oswego IL
331-732-XXXX GENEVA Geneva IL
331-746-XXXX KANEVILLE Kaneville IL
331-757-XXXX LEMONT Lemont IL
331-758-XXXX AURORA Aurora IL
331-771-XXXX ST CHARLES Saint Charles IL
331-775-XXXX DOWNERSGRV Downers Grove IL
331-777-XXXX DOWNERSGRV Downers Grove IL
331-788-XXXX GENEVA Geneva IL
331-800-XXXX W CHICAGO West Chicago IL
331-801-XXXX DOWNERSGRV Downers Grove IL
331-803-XXXX LEMONT Lemont IL
331-806-XXXX WHEATON Wheaton IL
331-808-XXXX PLANO Plano IL
331-811-XXXX IL
331-814-XXXX NAPERVILLE Naperville IL
331-825-XXXX GENEVA Geneva IL
331-826-XXXX ELMHURST Elmhurst IL
331-837-XXXX W CHICAGO West Chicago IL
331-850-XXXX BIG ROCK Big Rock IL
331-866-XXXX WHEATON Wheaton IL
331-867-XXXX YORKVILLE Yorkville IL
331-871-XXXX W CHICAGO West Chicago IL
331-888-XXXX WARRENVL Warrenville IL
331-899-XXXX LOMBARD Lombard IL
331-900-XXXX ELMHURST Elmhurst IL
331-901-XXXX ST CHARLES Saint Charles IL
331-903-XXXX DOWNERSGRV Downers Grove IL
331-911-XXXX IL
331-946-XXXX GLEN ELLYN Glen Ellyn IL
331-950-XXXX IL
331-958-XXXX IL
331-959-XXXX IL
331-976-XXXX IL
331-979-XXXX ELMHURST Elmhurst IL
331-980-XXXX AURORA Aurora IL
331-998-XXXX DOWNERSGRV Downers Grove IL
331-999-XXXX OSWEGO Oswego IL
Recent Signals

Latest complaint activity tied to 331

Complaint pages are the strongest indexing opportunity for this site right now, especially for exact phone numbers and toll-free exchanges.

FTC report from Orlando, FLORIDA

September 17, 2026 at 10:59 PM

331-212-8537 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 17, 2026 at 1:45 PM.

FTC report from Elkins, WEST VIRGINIA

September 17, 2026 at 8:02 PM

331-316-9405 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 17, 2026 at 6:08 AM.

FTC report from GEORGIA

September 17, 2026 at 5:37 PM

331-235-9973 was logged as a unwanted call. Violation date: September 17, 2026 at 5:20 PM.

FTC report from CALIFORNIA

September 17, 2026 at 4:10 PM

331-732-5710 was logged as a unwanted call. Violation date: September 15, 2026 at 4:13 PM.

FTC report from Durham, NEW YORK

September 17, 2026 at 1:59 PM

331-245-2371 was logged as a live voice. Category: Home improvement & cleaning. Violation date: September 17, 2026 at 1:55 PM.

FTC report from ILLINOIS

September 17, 2026 at 1:32 PM

331-256-5002 was logged as a live voice. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 16, 2026 at 9:50 AM.

FTC report from Geneva, ILLINOIS

September 17, 2026 at 12:45 PM

331-273-4249 was logged as a robocall. Category: Dropped call or no message. Violation date: September 9, 2026 at 3:59 PM.

FTC report from Lewes, DELAWARE

September 17, 2026 at 10:56 AM

331-212-9260 was logged as a robocall. Category: Calls pretending to be government, businesses, or family and friends. Violation date: September 17, 2026 at 10:36 AM.

FTC report from ILLINOIS

September 17, 2026 at 10:51 AM

331-316-8850 was logged as a live voice. Violation date: September 16, 2026 at 9:35 AM.

FTC report from Lewes, DELAWARE

September 17, 2026 at 10:50 AM

331-212-9260 was logged as a robocall. Violation date: September 17, 2026 at 2:36 PM.

FTC report from Andrews, TEXAS

September 17, 2026 at 9:55 AM

331-850-9827 was logged as a robocall. Category: Calls pretending to be government, businesses, or family and friends. Violation date: September 17, 2026 at 12:47 PM.

FTC report from Nampa, IDAHO

September 17, 2026 at 6:33 AM

331-356-8101 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 17, 2026 at 6:47 PM.

FTC report from Glendale, ARIZONA

September 16, 2026 at 10:47 PM

331-867-6994 was logged as a live voice. Category: Calls pretending to be government, businesses, or family and friends. Violation date: September 16, 2026 at 5:32 PM.

FTC report from Orland Park, ILLINOIS

September 16, 2026 at 9:36 PM

331-266-6134 was logged as a unwanted call. Category: Dropped call or no message. Violation date: September 16, 2026 at 11:20 AM.

FTC report from Henderson, NEVADA

September 16, 2026 at 9:30 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 6:41 AM.

FTC report from Henderson, NEVADA

September 16, 2026 at 9:28 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 9:27 AM.

FTC report from WASHINGTON

September 16, 2026 at 9:24 PM

331-788-8735 was logged as a live voice. Violation date: September 14, 2026 at 1:04 PM.

FTC report from Westmont, ILLINOIS

September 16, 2026 at 7:38 PM

331-400-1115 was logged as a live voice. Violation date: September 16, 2026 at 4:11 PM.

FTC report from Laramie, WYOMING

September 16, 2026 at 6:49 PM

331-600-0845 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 16, 2026 at 4:47 PM.

FTC report from Aspen, COLORADO

September 16, 2026 at 6:25 PM

331-247-1656 was logged as a robocall. Category: Calls pretending to be government, businesses, or family and friends. Violation date: September 16, 2026 at 4:23 PM.

FTC report from ILLINOIS

September 16, 2026 at 5:56 PM

331-400-1217 was logged as a live voice. Violation date: September 16, 2026 at 4:30 PM.

FTC report from ILLINOIS

September 16, 2026 at 5:17 PM

331-246-1561 was logged as a live voice. Violation date: September 16, 2026 at 7:43 AM.

FTC report from Buffalo Grove, ILLINOIS

September 16, 2026 at 3:46 PM

331-205-2245 was logged as a robocall. Category: Dropped call or no message. Violation date: September 13, 2026 at 6:21 PM.

FTC report from Myrtle Beach, NEW JERSEY

September 16, 2026 at 2:28 PM

331-400-4957 was logged as a live voice. Category: No Subject Provided. Violation date: September 15, 2026 at 1:45 PM.

FTC report from CALIFORNIA

September 16, 2026 at 2:20 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 6:40 AM.

FTC report from CALIFORNIA

September 16, 2026 at 2:13 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 8:59 AM.

FTC report from Schiller Park, ILLINOIS

September 16, 2026 at 1:24 PM

331-221-9007 was logged as a live voice. Violation date: September 16, 2026 at 1:15 PM.

FTC report from ILLINOIS

September 16, 2026 at 12:01 PM

331-271-8724 was logged as a robocall. Category: Dropped call or no message. Violation date: September 15, 2026 at 8:47 PM.

FTC report from ALABAMA

September 16, 2026 at 11:57 AM

331-888-1773 was logged as a robocall. Violation date: August 21, 2026 at 11:42 AM.

FTC report from Chester, SOUTH CAROLINA

September 16, 2026 at 11:56 AM

331-212-9187 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 16, 2026 at 11:51 AM.

FTC report from Plymouth, MASSACHUSETTS

September 16, 2026 at 9:00 AM

331-400-0537 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: August 12, 2026 at 9:13 AM.

FTC report from Aldie, VIRGINIA

September 16, 2026 at 8:49 AM

331-356-7524 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 15, 2026 at 5:02 PM.

FTC report from Springfield, ILLINOIS

September 15, 2026 at 9:54 PM

331-388-4676 was logged as a robocall. Violation date: August 8, 2026 at 4:56 PM.

FTC report from Waupaca, WISCONSIN

September 15, 2026 at 9:37 PM

331-758-6846 was logged as a live voice. Violation date: September 15, 2026 at 5:00 PM.

FTC report from Riverview, FLORIDA

September 15, 2026 at 9:01 PM

331-888-1773 was logged as a live voice. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 10:51 AM.

FTC report from Marble Falls, TEXAS

September 15, 2026 at 7:31 PM

331-899-3085 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 15, 2026 at 10:19 PM.

FTC report from San Diego, CALIFORNIA

September 15, 2026 at 6:48 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 9:37 AM.

FTC report from San Diego, CALIFORNIA

September 15, 2026 at 6:46 PM

331-888-1773 was logged as a robocall. Category: Reducing your debt (credit cards, mortgage, student loans). Violation date: September 10, 2026 at 7:14 AM.

FTC report from Forest Hill, MARYLAND

September 15, 2026 at 4:55 PM

331-356-8191 was logged as a unwanted call. Violation date: September 9, 2026 at 1:46 PM.

FTC report from ILLINOIS

September 15, 2026 at 2:58 PM

331-266-6217 was logged as a live voice. Violation date: September 15, 2026 at 1:55 PM.