Obtaining a Maritime Mobile Service Identity (MMSI) Number

A Maritime Mobile Service Identity (MMSI) is a nine-digit number that uniquely identifies ship stations, ship earth stations, coast stations, coast earth stations, and group calls. MMSI numbers are transmitted over a Digital Selective Calling (DSC) radio or Automatic Identification System (AIS) unit. Each vessel should have only one MMSI.

There are several ways to obtain an MMSI, depending on the user's situation:

• U.S. non-federal users
  • Non-commercial (recreational) boaters who stay in United States waters may obtain an MMSI from BoatU.S. or the United States Power Squadrons.
  • Commercial boaters, or those who operate U.S.-flagged vessels outside U.S. waters, must file Forms 159 and 605 with the U.S. Federal Communications Commission (FCC) to obtain an MMSI.
• U.S. federal users
  • Federal users must obtain an MMSI from their agency's Interdepartment Radio Advisory Committee (IRAC) representatives.
• Outside the United States
  • Boaters with vessels flagged in a different country must obtain an MMSI from that country's telecommunications authority or ship registry.

The FCC provides a searchable database of all U.S. MMSIs.

See the U.S. Coast Guard Navigation Center's website for more information about MMSIs.