What does MMSI stand for?

• A. Maritime Mobile Service Identity Number
• B. Maritime Monitoring System Identifier
• C. Marine Mobile Safety Information
• D. Maritime Master System Identifier

Answer: (A)

MMSI is a unique numeric identifier used in maritime radio communications to identify ships, coast stations, and distinct groups. This identifier lets digital calls and AIS broadcasts reach the intended recipient and helps route distress or routine messages accurately. In practice, vessels and shore stations register an MMSI, which is typically a nine-digit number for ship stations, with parts of the digits encoding country and type of user. The term specifically expands to Maritime Mobile Service Identity, sometimes shown with “Number” at the end in some sources, but the essential idea is the same: it’s the dedicated identity used in maritime communications. Other phrasing presented isn’t standard terminology in this field.