The 312 area code is a telephone area code serving the city of Chicago, Illinois, including downtown, the Chicago Loop, and its immediate environs. To start a free reverse phone lookup, simply enter the full 10-digit number (including the 312 area code) below and access available caller information such as name, address, and more.
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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 reverse phone lookup will analyze the three-digit prefix of any 312 area code phone number and will show which telecommunications company and rate center it was initially assigned to. This prefix code data may help to determine the U.S. carrier, Illinois geographic region, and local calling area associated with the phone number.
| 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 |
| 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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