Maritime Mobile Service Identity, or MMSI is a key component for ensuring your safety while boating. Additionally, a MMSI number allows you to use Digital Selective Calling(DSC).
DSC technology allows boaters to send a digital call directly to other DSC-equipped vessels and shore stations, somewhat like a telephone call. Once the DSC call has been confirmed, both parties are automatically switched to a working voice channel. If properly installed, one push of a button in an emergency, and your DSC radio will send an automated digital distress alert consisting of your MMSI identification number (if it was input), and position (if it is interfaced with a GPS receiver) to other DSC-equipped vessels and search & rescue facilities. When they respond, they will automatically be connected to whatever channel your radio is set to. Of course, if you haven't interfaced it with your GPS and MMSI number, the only thing you will do is send an alarm.
One other nifty feature is that your MMSI number can act as a direct homing device to other similarly equipped radios that have your number. It’s a like a VHF phone number. You program in your friend’s MMSI and that radio is automatically and directly called without having to hail them on a public frequency. Of course, as soon as they answer, they will connect with you on the radio frequency you are standing by on, so keep in mind it’s still a public channel. Make sure you are standing by on a working channel not on a reserved frequency like channel 16.
Some Basic MMSI info from USCG: https://www.navcen.uscg.gov/?pageName=mtMmsi
You can get your free MMSI at the USPS MMSI Registration page:
Or at the BoatUS MMSI page:
Here are some fact filled article on benefits of registering and programming your MMSI: http://cruising.coastalboating.net/Seamanship/Radio/DSC.html
A good article summarizing Use of VHF & DSC radio: https://www.sailmagazine.com/cruising/are-you-using-your-vhf-radio-correctly
Good overall MMSI, DSC, GPS integration article: http://wow.uscgaux.info/content.php?unit=170&category=dsc-vhf-radio-rescue-21
Watch a few short videos describing the value of having a DSC VHF Radio and an MMSI: https://www.youtube.com/watch?v=AiXN8pNoA0I
NMEA Consumer VHF DIY install brochure
Our Squadron's Group MMSI Information
Our Squadron;s Group MMSI is: 033818109. Members are encouraged to enter this Group MMSI into their DSC Group Directory and use it to communicate with Club members. We also recommend that you also enter VHF Channel-72 as the DSC call response channel when calling. When the Group MMSI is used to make a call all squadron members that have entered 033818109 into the Group Directory on their VHF will be notified. When they acknowledge the call their radio will be switched to the working channel where other members are tuned to on their radios.
MMSI Test Calls
For VHF DSC radios equipped with the Test Call feature, test transmissions should be made to the US Coast Guard MMSI 003669999 to receive an automated VHF DSC test response. You must use the “Test Call” category of your radio because “Individual” category calls to this address will not receive an automated response. ...