Area Code 240-205 located in ROCKVILLE, MONTGOMERY, MD, more detail is as below. Place NPA (Numbering Plan Area) : 240 NXX (Local Number Prefix) : 205 City : ROCKVILLE County : MONTGOMERY State : MD (Maryland) NXX Use Type : Wireless NXX Intro Version : 2004-01-27 FIPS (Federal Information Processing Standards) : 24031 LATA (Local Access Transport Area) : 236 Rate Center : WSNGTNZN10 ZIP Code Count : 0 ZIP Code Frequency : Most frequently occurring ZIP Code, although percentage is unknown. ZIP Code : 20851 Other Information NPANXX : 240205 County Population : 0 Switch CLLI (Common Language Location Identifier) : BTVLMD18GT0 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 Overlay : L Company : NEW CINGULAR WIRELESS PCS, LLC - DC OCN (Operating Company Number) : 4036 Coverage Area Name : CABIN JOHN Latitude : 38.9212 Longitude : -77.2141 ‹ previous : 240-205 next › : 240-206 Telephone Number List 240-205-0000 ~ 240-205-9999