How to Register for an MMSI

Written by theon weber
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How to Register for an MMSI
An MMSI identifies a shipboard radio. (boat image by pearlguy from

The radio equipment on your boat should be assigned a Maritime Mobile Service Identity, which identifies its station to receivers. MMSIs double as licenses to operate maritime radios, and are assigned, like all radio call signs, by the International Telecommunications Union in Geneva, Switzerland. One of the primary uses of the MMSI is to identify your boat automatically when you make a distress call. In the United States, domestic MMSI numbers are available for free from BoatUS, an organisation authorised to assign MMSIs by the Federal Communications Commission.

Skill level:
Moderately Easy


  1. 1

    Navigate to BoatUS' MMSI website (see Resources).

  2. 2

    Click "Free MMSI Number."

  3. 3

    Follow the on-screen directions and let the site guide you through the MMSI registration process. You will need your vessel's documentation or registration number, as well as the telephone numbers of two emergency contacts and of any wireless or cellular devices you plan to use on board.

  4. 4

    Call the Federal Communications Commission at 888-225-5322 if you wish to receive a number directly from them. If you plan to travel or communicate with ships outside U.S. waters, it's best to register directly with the FCC, as this will place your MMSI into the International Search and Rescue Database. Unlike BoatUS, however, the FCC will require a fee from you.

Tips and warnings

  • If you are a U.S. federal employee operating a boat in the course of your duty, you should obtain an MMSI from your agency's radio spectrum management office rather than through the public channels.
  • The regulatory body in charge of assigning MMSIs varies from country to country. If you are outside the U.S. and you need to obtain an MMSI, contact your country's communications organisation.

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