Look up any phone number starting with 312 to identify the owner name, address, spam reports, and more. The 312 area code is serving the city of Chicago, Illinois, including downtown, the Chicago Loop, and its immediate environs.
Enter a full 10-digit number to identify the caller and whether it has been reported as spam.
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Area code 312 serves the city of Chicago, specifically downtown, the Chicago Loop, and its immediate surrounding areas. It is bounded by North Avenue on the north, Western Avenue on the west, and 35th Street on the south, with Lake Michigan to the east.
Area code 312 is part of an overlay complex with area code 773 and area code 872 . 312 was created in 1947. Area code 773 was introduced on October 11, 1996, and area code 872 was introduced on November 7, 2009. All local calls in Chicago require ten-digit dialing.
Area code 312 is a general purpose code which was placed in service on January 1, 1947.
Our Illinois phone number lookup for the 312 area code analyzes the three-digit prefix to identify the initially assigned telecommunications company and rate center. This prefix code data may help to determine the U.S. carrier, Illinois geographic region, and local calling area associated with the phone number.
Phone numbers follow the following structure under the North American Numbering Plan:
Understanding the area code can help you determine if a call is local to your area. However, keep in mind that due to mobile number portability and VoIP services, the caller may be anywhere in the United States, so it’s best to search for the most recent phone number details.
| Company | Number of Prefixes |
|---|---|
| ILLINOIS BELL TEL CO | 306 |
| NEW CINGULAR WIRELESS PCS, LLC - IL | 65 |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL | 51 |
| MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 28 |
| T-MOBILE USA, INC. | 28 |
| LEVEL 3 COMMUNICATIONS, LLC - IL | 26 |
| SPRINT SPECTRUM, L.P. | 23 |
| TELEPORT COMMUNICATIONS AMERICA, LLC - IL | 16 |
| BANDWIDTH.COM CLEC, LLC - IL | 10 |
| ONVOY, LLC | 9 |
| OVATION COMMUNICATIONS OF ILLINOIS, INC. | 9 |
| RCN TELECOM SERVICES OF ILLINIOS, INC. - IL | 9 |
| MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 8 |
| PEERLESS NETWORK OF ILLINOIS, LLC - IL | 8 |
| AT&T - LOCAL | 7 |
| FIRST COMMUNICATIONS, LLC - IL | 6 |
| XO ILLINOIS, INC. | 6 |
| GLOBAL CROSSING LOCAL SERVICES, INC. - IL | 5 |
| USA MOBILITY WIRELESS, INC. | 4 |
| COMCAST IP PHONE, LLC | 3 |
| METROPCS, INC. | 3 |
| AMERICAN MESSAGING SERVICES, LLC | 2 |
| FIRST COMMUNICATIONS, LLC | 2 |
| RCLEC, INC. - IL | 2 |
| US XCHANGE OF ILLINOIS LLC DBA CHOICE ONE COMM IL | 2 |
| ACCESS ONE, INC. - IL | 1 |
| AT&T CORP. | 1 |
| CENTURYLINK COMMUNICATIONS, LLC | 1 |
| GETGO COMMUNICATIONS LLC - IL | 1 |
| LEVEL 3 TELECOM OF ILLINOIS, LLC - IL | 1 |
| NUSO, LLC | 1 |
| PAETEC COMMUNICATIONS, INC. - IL | 1 |
| YMAX COMMUNICATIONS CORP. - IL | 1 |
Carrier names have been updated from their original FCC assignments to reflect current companies following mergers, acquisitions, and rebranding. Updates were determined using AI-assisted research and may not be accurate or reflect up to date changes. This data is provided without warranties of accuracy or completeness.
| Rate Center | Number of Prefixes |
|---|---|
| CHICGOZN01 | 625 |
| HINSDALE | 5 |
| LA GRANGE | 5 |
| WHEELING | 5 |
| NORTHBROOK | 3 |
| CHICGOZN04 | 1 |
| CHICGOZN07 | 1 |
| ROSELLE | 1 |
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