Ask Sail: MMSI Numbers

Perry Close Boston, Massachusetts asks:

I just purchased an ocean-going sailboat at a foreclosure sale and will soon install an SSB radio and an AIS transponder. The existing VHF radio is tied into the GPS receiver, and there is an existing maritime mobile ship identity (MMSI) number that comes up on the VHF display when I turn it on. The paperwork on the boat shows that the MMSI number came from one of the towing agencies. May I use this same number for the new SSB and AIS equipment I want to install?

Gordon West Replies

The MMSI number currently assigned to your VHF radio cannot be transferred to you and should be cancelled by the former owner. MMSI numbers issued by towing companies or the Power Squadron are normally intended for use with DSC-VHF radios used in domestic waters. What you need is a ship station license issued by the Federal Communications Commission. This license, good for 10 years, includes an MMSI number that can be programmed into your VHF, SSB and AIS equipment. If you aren’t leaving domestic waters and don’t install an SSB radio, you won’t need an FCC license, but you’ll still need a new number.
You may need an NMEA-certified technician to reset the MMSI number circuit on your VHF radio. Ask the tech to input your new FCC MMSI number into both the VHF and SSB radios. The AIS transponder will come pre-programmed with your new number, after you receive your ship station license. You can study the licensing process at You will also need a Restricted Operator permit, unless you previously held one, if you are leaving the country with your radios.


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