Area Code 301-217 located in POTOMAC, MONTGOMERY, MD, more detail is as below. Place NPA (Numbering Plan Area) : 301 NXX (Local Number Prefix) : 217 City : POTOMAC County : MONTGOMERY State : MD (Maryland) NXX Use Type : Landline NXX Intro Version : 1994-02-04 FIPS (Federal Information Processing Standards) : 24031 LATA (Local Access Transport Area) : 236 Rate Center : WSNGTNZN10 ZIP Code Count : 110 ZIP Code Frequency : 17 ZIP Code : 20854 Other Information NPANXX : 301217 County Population : 0 Switch CLLI (Common Language Location Identifier) : RKVLMDRVDS1 MSA CBSA (Core Based Statistical Area) : Washington-Arlington-Alexandria, DC-VA-MD-WV MSA CBSA Code (Core Based Statistical Area) : 47900 Time Zone : Eastern (GMT -05:00) Observes Daylight Saving Time : Yes Company : VERIZON MARYLAND, INC. OCN (Operating Company Number) : 9212 Coverage Area Name : ROCKVILLE Latitude : 39.0815 Longitude : -77.1503 ‹ previous : 301-216 next › : 301-217 Telephone Number List 301-217-0000 ~ 301-217-9999