Area Code 303-306 located in DENVER, DENVER, CO, more detail is as below. Place NPA (Numbering Plan Area) : 303 NXX (Local Number Prefix) : 306 City : DENVER County : DENVER State : CO (Colorado) NXX Use Type : Landline NXX Intro Version : 1996-04-15 FIPS (Federal Information Processing Standards) : 08031 LATA (Local Access Transport Area) : 656 Rate Center : DENVERSLVN ZIP Code Count : 801 ZIP Code Frequency : 46 ZIP Code : 80231 Other Information NPANXX : 303306 County Population : 0 Switch CLLI (Common Language Location Identifier) : DNVRCOSLDS0 MSA CBSA (Core Based Statistical Area) : Denver-Aurora, CO MSA CBSA Code (Core Based Statistical Area) : 19740 Time Zone : Mountain (GMT -07:00) Observes Daylight Saving Time : Yes Company : QWEST CORPORATION OCN (Operating Company Number) : 9636 Coverage Area Name : AURORA Latitude : 39.6715 Longitude : -104.8616 ‹ previous : 303-306 next › : 303-307 Telephone Number List 303-306-0000 ~ 303-306-9999