What is a MMSI?

Modern marine radios now feature Digital Selective Calling (DSC) for routine operations and for automated distress hailing. These features can only be used if your radio is programmed with a unique code called a Maritime Mobile Service Identity, or MMSI.

The Maritime Mobile Service Identity is a unique nine digit number that identifies transmitted signals within the Global Maritime Distress and Safety System (GMDSS.) It functions like a telephone number for the devices on your boat.

The MMSI is assigned to a vessel, and the same MMSI is programmed into all shipboard equipment that transmits and receives digital signals, including VHF radio, medium and high frequency radios, AIS (Automatic Identification System), and INMARSAT satellite terminals. There is an important exception: the EPIRB (Emergency Position Indicating Radio Beacon), which must be registered separately from this site through the NOAA web site.

MMSIs consist of a three digit country code (called a MID) and a six digit station code. The United States MID codes are 366, 367, 368, 379, 559, 303, 338, and 358.

United States Power Squadrons is authorized by the Federal Communications Commission and the US Coast Guard  to issue MMSIs to US flagged vessels not subject to Safety of Life at Sea (SOLAS) Convention requirements. This includes almost all recreational boats.

Vessels required to have FCC ship station licenses, including US flagged pleasure craft making international voyages, must obtain their MMSIs directly from the Federal Communications Commission.

Our Canadian friends can obtain MMSIs from Industry Canada / Industrie Canada.

It is illegal for you to self-assign a MMSI. Use of an unauthorized identity can seriously compromise search and rescue efforts, including misdirection of SAR forces and alerting of the wrong emergency contacts.


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