Any DSC radio must have an MMSI (Maritime Mobile Service Identity) number programmed into it so the emergency feature works. This number identifies the vessel; you will fill out an application form with the boat information. If the boat will operate only in U.S. waters, you can get a number for free from BoatUS (www.BoatUS.com/MMSI).
If a U.S.-registered boat travels to foreign waters (Canada, Mexico, the Bahamas and the Caribbean or abroad) you will need to get the MMSI number, for a small fee, from the FCC at
After you’ve hooked up the DSC radio to a GPS, read the radio manual and see what else a DSC radio can do for you. There is a very nice tutorial about DSC radio on the BoatUS website at http://www.boatus.com/foundation/dsc/player.html.