Mobile Maritime Service Identity (MMSI)

A nine-digit number that uniquely identifies a ship station, coast station, group, or aircraft in the maritime mobile service, used by DSC, AIS, and Inmarsat. Assigned by the flag administration under ITU-R Recommendation M.585, a ship MMSI begins with a three-digit Maritime Identification Digits (MID) code identifying the country, for example 232 to 235 for the UK, 366 to 369 for the USA. Coast stations prefix 00, group calls 0, and SAR aircraft 111. The MMSI is programmed once and travels with the vessel’s call sign and identity.