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MMSIs for Federal Vessels

Obtaining and Registering an MMSI

Federal users can obtain MMSI assignments from their agency radio spectrum management office in accordance with Section 6.6 of the NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management. Contact for guidance concerning MMSIs used on Federal Vessels, including finding your agency's contact information for MMSI assignment and registration. U.S. Coast Guard users can obtain an MMSI through Commandant CG-672 in accordance with Commandant Instruction M2000.3 series. U.S. Coast Guard Auxiliary surface vessel operators should request assignment of MMSIs using the same method as a U.S. Non-Federal user. Except for AIS-SARTs and VHF handhelds not intended for dedicated use on the vessel, each radio on the vessel must use the same, identical MMSI.

Maintaining your MMSI Registration or Transferring your Vessel or your Radio

U.S. Coast Guard search and rescue authorities rely on MMSI registration information whenever the distress button on a DSC-equipped VHF marine radio is pressed.  For that reason, it is essential that MMSI registration be kept current. Please notify your spectrum management office or office responsible for MMSIs to notify them whenever the radio is removed from a vessel, transferred to another vessel, surplused, or when other significant changes are made. If you permanently remove any AIS or DSC-equipped radio from a vessel, then the removed radio equipment must have its MMSI deleted.

Deleting own-ship MMSI
ITU regulations prevent you from deleting own-ship MMSI without advice from the radio manufacturer. You will need to contact the manufacturer or its representative to determine how MMSIs are deleted on that particular model, regardless of whether it is DSC-equipped radio or a Class A or Class B AIS unit. For some models, deleting is easy, entering a code provided by the manufacturer. For others, it is more difficult, requiring a visit by a dealer or the radio be removed and returned to the manufacturer. For that reason, anyone purchasing a DSC-equipped radio or AIS is urged to find out how own-ship MMSIs are deleted on that radio prior to purchase.

MMSI Format

All ship MMSIs use the format M1I2D3X4X5X6X7X8X9 where in the first three digits represent the Maritime Identification Digits (MID) and X is any figure from 0 to 9. (Hint: Ships transmitting with an MMSI not starting with the digits 201-775 are likely doing so improperly, and may be subject to enforcement action).

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