Area Code 603-320 located in MILFORD, HILLSBOROUGH, NH, more detail is as below. Place NPA (Numbering Plan Area) : 603 NXX (Local Number Prefix) : 320 City : MILFORD County : HILLSBOROUGH State : NH (New Hampshire) NXX Use Type : Wireless NXX Intro Version : 2000-08-20 FIPS (Federal Information Processing Standards) : 33011 LATA (Local Access Transport Area) : 122 Rate Center : NASHUA ZIP Code Count : 1 ZIP Code Frequency : 50 ZIP Code : 03055 Other Information NPANXX : 603320 County Population : 0 Switch CLLI (Common Language Location Identifier) : MNCHNHCOHAX MSA CBSA (Core Based Statistical Area) : Manchester-Nashua, NH MSA CBSA Code (Core Based Statistical Area) : 31700 Time Zone : Eastern (GMT -05:00) Observes Daylight Saving Time : Yes Company : NEW CINGULAR WIRELESS PCS, LLC - DC OCN (Operating Company Number) : 4036 Coverage Area Name : NASHUA Latitude : 42.7610 Longitude : -71.4634 ‹ previous : 603-320 next › : 603-321 Telephone Number List 603-320-0000 ~ 603-320-9999