I went ahead and input my one and only MMSI into my new (second) DSC radio. I have the radios hooked up to different GPS units in case one should die at an inopportune moment. They have independent antennas placed on opposite sides of the boat. Every battery on the boat can be tied into their power supply lines. We have a non-DSC walkie talkie in our ditch kit, right along with our personal locator beacon. Rich Gano CALYPSO (GB-42 #295) Southport, FL (near Panama City)