Navigation Center
United States Coast Guard
U.S. Department of Homeland Security

Search and Rescue Watchstanders

Valid MMSIs used in distress alerts

Valid MMSIs used in DSC distress alerts always begin with the following digits:

  • 201xxxxxx through 775xxxxxx. These three digits are MIDs assigned to individual countries by the ITU.  776xxxxxx – 799xxxxxx may also be allocated in the future without notice.
  • 98MIDxxxx are used by craft associated with a parent ship, such as launches. They are not used in the U.S.
  • 972xxxxxx are used by Maritime Survivor Locating Devices (MSLDs). These MMSIs are unregistered.

MMSI databases

The FCC allocates blocks of MMSI for assignment to ships through its Universal Licensing System, to federal ships through NTIA, and to recreational vessels and other non-compulsory users through private license-by-rule providers BOAT US 1-800-563-1536, U.S. Power Squadron 1-888-367-8777, Shine Micro 1-360 437-2503, and Sea Tow 1-800-4-SEATOW (Sea Tow is no longer accepting new registrations but is maintaining existing ones). All providers except NTIA are or are in the process of submitting data weekly into Marine Information for Safety and Law Enforcement (MISLE) database.  However, MISLE can only accept portions of the data provided.  Consequently, direct contact with MMSI providers is necessary to obtain complete registration information.

MMSI data collected by license-by-rule providers contains more detailed information than data collected by MISLE, as shown in MMSI MOU Attachment A MMSI Data Record.

BOAT US allows SAR watchstanders password-controlled direct access to its database. FCC ULS access requires no password but data is limited. The FCC Operations Center 202-418-1122 is also available on a 24 hours a day, 365 days a year basis supporting maritime search and rescue, including geolocation and MMSI. Access to US Power Squadrons, Shine Micro, Sea Tow and NTIA databases currently requires personal intervention. Point of contact information for search and rescue response purposes is available upon request.

The FCC maintains a listing of MMSI allocated to various MMSI providers here, useful in identifying in which database a particular MMSI has been registered. This listing does not include MMSIs that were later transferred to a different provider.

MMSIs assigned outside the United States should be listed in the ITU Maritime mobile Access and Retrieval System (MARS) Ship Station Search website, or from a Rescue Coordination Center in the country from which the MMSI was assigned.

Return to MMSI Page