Area Code +1-301-(2121000...2121999) located in Rockville, Maryland (MD), more detail is as below. Place International Dialing Code : 1 International Prefix : 011 National Prefix : 1 National Destination Code : 301 Subscriber Number From : 2121000 Subscriber Number To : 2121999 National Destination Code Length : 3 Uses National Destination Code : Yes National Significant Number Length : 10 Number Type : G (Geographic Land Line, Fixed Line) Carrier Name : VERIZON MARYLAND INC Click here to buy United States Area Code Database Other Information Language Code : en (English) Country Number : 840 (United States) Country Code : US (United States) Region Code : MD Region Name : Maryland City : Rockville Timezone : America/New_York Coordinated Universal Time : -05:00 Daylight Saving Time : Yes National Significant Number Minimum Length : 10 Latitude : 39.0900 Longitude : -77.1600 ‹ previous : +1-301-(2120000...2120999) next › : +1-301-(2122000...2122999) Dialling Instructions For trunk calls: 0 301 2121000 (Trunk Code + National Destination Code + Subscriber Number) For international calls: 011 1 301 2121000 (International Prefix + International Dailing Code +National Destination Code + Subscriber Number) Telephone Number List 2121000 ~ 2121999 (Count: 1,000) Example: +1-301-2121000 / 0111-301-2121000 (1301-2121000 / 1-301-2121000) +1-301-2121001 / 0111-301-2121001 (1301-2121001 / 1-301-2121001) +1-301-2121002 / 0111-301-2121002 (1301-2121002 / 1-301-2121002) +1-301-2121003 / 0111-301-2121003 (1301-2121003 / 1-301-2121003) +1-301-2121004 / 0111-301-2121004 (1301-2121004 / 1-301-2121004) ...+1-301-xxxxxxx / 0111-301-xxxxxxx (1301-xxxxxxx / 1-301-xxxxxxx) ...+1-301-2121995 / 0111-301-2121995 (1301-2121995 / 1-301-2121995) +1-301-2121996 / 0111-301-2121996 (1301-2121996 / 1-301-2121996) +1-301-2121997 / 0111-301-2121997 (1301-2121997 / 1-301-2121997) +1-301-2121998 / 0111-301-2121998 (1301-2121998 / 1-301-2121998) +1-301-2121999 / 0111-301-2121999 (1301-2121999 / 1-301-2121999)