Here is some basic information about MMSI numbers, what they are, and why they are important. In addition, you will find information on what to do if you sell your boat.


What is an MMSI Number?

The MMSI number is akin to a cell number and is a unique number assign to a Digital Selective Calling Radio and used to identify the vessel. The information provided when obtaining an MMSI number is provided to the United States Coast Guard (USCG) for use in emergency situations. MMSI use and registration greatly assists the USCG in responding to an alert since it contains a description of the vessel and telephone numbers used to contact the vessel’s owner or point of contact in an emergency.


  • MMSI numbers are issued by the FCC if the vessel requires a Station License, otherwise (for recreational use) they can be obtained from Boat U.S. (https://www.boatus.com/mmsi), United States Power Squadron (https://www.usps.org/php/mmsi_new/), and Shine Micro (https://www.shinemicro.com) often at no charge.
  • Please note that Sea Tow no longer issues new MMSI numbers, however they will still allow you to update an MMSI number that was originally registered through them (https://seatow.com/marine-services/mmsi/)
  • Recreational MMSI numbers are for US registered or documented recreational vessels under 65’ (65 feet) that are not visiting or communicating with foreign ports.
  • The registration data provided during registration is only transferred into the U.S. Coast Guard Search & Rescue Database (MISLE). International search & rescue agencies do not have access to this registration data.

Those having MMSIs should keep registration information current, including phone numbers, address, name and type of boat. See below for updating your MMSI.


If you sell the boat

  • If you kept all the radios that had the same MMSI number programmed into them, you can update your registration with the new boat information when/if a new boat is bought.
  • If all the radios that are programmed with the MMSI number have been given to the new owner, you must transfer the MMSI number to the new owner’s information by logging into your MMSI account and selecting the “Transfer to New Owner” button.
  • If you do not know which organization registered your MMSI number, you can identify that organization by comparing the existing MMSI against those listed in the document: https://navcen.uscg.gov/sites/default/files/pdf/MMSIAllotments.pdf
  • Transferring the MMSI to a new owner cancels your MMSI registration and avoids having any future distress calls from that MMSI number linked to you/your info. The new owner will then receive an email with instructions on how to claim the MMSI number.


Transferring or Updating the MMSI Number

If you wish to transfer the MMSI number...

  • You can typically transfer the MMSI number by contacting the issuing organization
  • If you retained one or more of the radios with the MMSI number and the new owner also has one or more radios with the MMSI number programmed into it, you will need to work with the new owner to determine who is going to be responsible for obtaining a new MMSI number and having the radio(s) reprogrammed. It is critically important that two individuals are NOT using the same MMSI number on different boats.

If you buy a radio that has an existing MMSI number programmed into it...

  • If the MMSI number was assigned by, for example, BoatUS and the previous owner has cancelled their registration, BoatUS can transfer that programmed MMSI number to the new owner.
  • If the previous owner has not closed the account, they will attempt to contact that customer to verify that they are not still using that number in another radio.
  • If the previous owner cannot be contacted or is still improperly using the MMSI, you will need to reprogram the radio with a new number.
  • To check if the MMSI was assigned through BoatUS, you can email here: mmsi@boatus.com. (*If not through BoatUs, you should be able to contact Shine Micro, Sea Tow, or US Power Squadrons in a similar manner)
  • If you need to obtain a new MMSI number and program it into a radio with an existing MMSI number

The already programmed MMSI number must first be removed from the radio. This must be done at your boat/radio dealer, or an authorized marine dealer. Contact the issuing organization for your MMSI to find a list of local dealers to program the radio. Dealers can contact Cobra at 800-543-1608 to inquire about resetting radio.


Important notes

  • When programming the MMIS number into the radio, you only have 2 attempts to do it correctly (initial entry and confirmation of the entry.
  • Once the radio has accepted the MMSI number, it cannot be changed easily.
  • To program a new (or the correct) MMSI number, please see a marine dealer for assistance as the reset instruction information is not available to the public due to FCC regulations.
  • Alternatively, you can call 800-543-1608 to arrange to send your radio in (current models only!) and we can perform this service for you. The service fee is $39.95 and it takes approximately 2-3 weeks to complete the process from when we sign for the package to when you have the radio back in your hands.

**For customers outside the US, please contact one of our Global Partners HERE