Area Code 303-999 located in DENVER, DENVER, CO, more detail is as below. Place NPA (Numbering Plan Area) : 303 NXX (Local Number Prefix) : 999 City : DENVER County : DENVER State : CO (Colorado) NXX Use Type : Landline NXX Intro Version : 8/24/2007 FIPS (Federal Information Processing Standards) : 08031 LATA (Local Access Transport Area) : 656 Rate Center : DENVER ZIP Code Count : 0 ZIP Code Frequency : 0 ZIP Code : 80204 Other Information NPANXX : 303999 County Population : 0 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 : COMCAST PHONE OF COLORADO, LLC - CO OCN (Operating Company Number) : 320A Coverage Area Name : DENVER Latitude : 39.7454 Longitude : -105.0512 ‹ previous : 303-998 next › : 304-200 Telephone Number List 303-999-0000 ~ 303-999-9999