Marine Mobile Service Identity
MMSI Overview
Maritime Mobile Service Identities (MMSIs) are nine digit numbers used by maritime digital selective calling (DSC), automatic identification systems (AIS) and certain other equipment to uniquely identify a ship or a coast radio station. MMSIs are regulated and managed internationally by the International Telecommunications Union in Geneva, Switzerland, just as radio call signs are regulated. The MMSI format and use is documented in Article 19 of the ITU Radio Regulations and ITU-R Recommendation M.585-6, available from the ITU.
How to Obtain an MMSI Assignment
In the United States, the National Telecommunications Administration (NTIA) provides MMSIs to federal users, and the Federal Communication Commission (FCC) provides MMSIs to everyone else. NTIA is as Executive Branch agency under the Department of Commerce, and the FCC is an independent agency.
U.S. Non-Federal User
In order to obtain an MMSI, mariners required by regulation to carry a marine radio and those who travel outside the U.S. or Canada to foreign ports must apply to the Federal Communications Commission for a ship station license or an amendment to a ship station license. State and local governments can generally obtain an FCC ship station license at no charge.
Mariners not required to carry a marine radio (e.g. recreational boaters) and who remain in U.S. waters can obtain an MMSI through approved organizations such as BOAT US 1-800-563-1536, U.S. Power Squadron, and Shine Micro (primarily for AIS).
U.S. Federal User
Federal users can obtain MMSI assignments from their agency radio spectrum management office in accordance with Section 6.6 of the NTIA Manual. Official DHS and 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.
Obtaining MMSIs for DSC-equipped VHF Handhelds
A handheld VHF transceiver with DSC and an integral global navigation satellite system (e.g. GPS) not intended for dedicated use on a particular ship (e.g. a diver’s radio) should be assigned a unique 9-digit number in the format 81M2I3D4X5X6X7X8X9. While currently means do not exist within the U.S. to assign such identities, the Coast Guard has been in discussions with the Federal communications Commission and others on implementing them.
In the interim, VHF handhelds used in the United States should use the MMSI assigned to the ship to which the handheld is primarily associated, even if another radio on that ship uses the same MMSI. Non-commercial users of VHF handhelds not primarily associated with any single ship may use an MMSI provided by an organization such as BOAT US and U.S. Power Squadron (see above). VHF handhelds should not be used ashore absent FCC or NTIA authorization allowing such use.
