Some cities covered by area code 631 are Brentwood, Centereach, Central Islip, Commack, Copiague, Coram, Deer Park, Dix Hills, East Northport, East Patchogue, Hauppauge, Holbrook, Huntington Station, Medford, North Bay Shore, North Lindenhurst, Ronkonkoma, Selden, Shirley, Smithtown, West Babylon, West Islip