Area Code 312-506 located in CHICAGO, COOK, IL, more detail is as below. Place NPA (Numbering Plan Area) : 312 NXX (Local Number Prefix) : 506 City : CHICAGO County : COOK State : IL (Illinois) NXX Use Type : Landline NXX Intro Version : 2004-12-13 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 : 312506 County Population : 0 Switch CLLI (Common Language Location Identifier) : CHCGIL24DS7 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 : CIMCO COMMUNICATIONS, INC. - IL OCN (Operating Company Number) : 5917 Coverage Area Name : CHICAGO Latitude : 41.8839 Longitude : -87.6369 ‹ previous : 312-505 next › : 312-506 Telephone Number List 312-506-0000 ~ 312-506-9999