Before you can use the digital selective calling feature on your VHF radio, you will need to have an MMSI number. If you do not already have an MMSI number for your boat you may obtain one from www.boatus.com/MMSI.

Once your MMSI number is assigned, you need to program it into your radio, according to the instructions in your radio manual. To fully utilize the DSC feature, you will also need to connect your GSP to your radio. Once you've done that, when you press the Emergency Call Button on the radio, the radio will tell the Coast Guard who and where you are, so they can help you.

Without the MMSI number, the Coast Guard has no idea whether the call is from a ship, a 16-foot runabout, a 50-foot sailing yacht, a canoe, or what. They also do not know where to look for you.