Area Code 312-232 located in CHICAGO, COOK, IL, more detail is as below. Place NPA (Numbering Plan Area) : 312 NXX (Local Number Prefix) : 232 City : CHICAGO County : COOK State : IL (Illinois) NXX Use Type : Wireless NXX Intro Version : 2003-11-11 FIPS (Federal Information Processing Standards) : 17031 LATA (Local Access Transport Area) : 358 Rate Center : CHICGOZN01 ZIP Code Count : 0 ZIP Code Frequency : Second most frequently occurring ZIP Code, although percentage is unknown. ZIP Code : 60661 Other Information NPANXX : 312232 County Population : 0 Switch CLLI (Common Language Location Identifier) : CHCGILWBX6Z MSA CBSA (Core Based Statistical Area) : Chicago-Naperville-Joliet, IL-IN-WI MSA CBSA Code (Core Based Statistical Area) : 16980 Time Zone : Central (GMT -06:00) Observes Daylight Saving Time : Yes Company : AMERICAN MESSAGING (AM), INC. OCN (Operating Company Number) : 9748 Coverage Area Name : CHICAGO Latitude : 41.8839 Longitude : -87.6369 ‹ previous : 312-231 next › : 312-232 Telephone Number List 312-232-0000 ~ 312-232-9999