a maritime mobile service identity (mmsi) is a series of nine digits which are sent in digital form over a radio frequency channel in order to uniquely identify ship stations, ship earth stations, coast stations, coast earth stations, and group calls. these identities are formed in such a way that the identity or part thereof can be used by telephone and telex subscribers connected to the general telecommunications network to call ships automatically. ==types== there are now six kinds of maritime mobile service identities: * ship station identities, * group ship station identities, * coast station identities, * group coast station identities. * sar aircraft * navigational aids and craft associated with a parent ship ==maritime identification digits (mid)== an mid consists of three digits, always starting with a number from 2 to 7 (assigned regionally). a second mid can be assigned once the first or subsequently allocated mid is more than 80% exhausted, and the rate of assignments is such that 90% exhaustion is foreseen. a listing of mids assigned to each country is written in table 1 of itu radio regulations appendix 43. ==the first digit of an mmsi== the initial digits of an mmsi categorize the identity, as defined in by recommendation m.585. the meaning of the first digit is: * 0 ship group, coast station, or group of coast stations * 1 for use by sar aircraft (111midaxx)the seventh digit ("a") may, but does not have to, designate where the aircraft is fixed-wing (a = 1) or a helicopter (a = 5) if desired. the "a" digit can also simply be used like the other "x" digits if the distinction is not desired. first specified in this revision; carried forward in newer versions of the m.585 recommendation. * 2-7 mmsi's used by individual ships, beginning with an mid: ** 2 europe (e.g., italy has mid 247; denmark has mids 219 and 220) ** 3 north and central america and caribbean (e.g., canada, 316; panama, 351, 352, 353, 354, 355, 356, 357, 370, 371, 372, and 373) ** 4 asia (e.g., prc, 412, 413, and 414; maldives, 455) ** 5 oceana (australia, 503) ** 6 africa (eritrea, 625) ** 7 south america (peru, 760) * 8 handheld vhf transceiver with dsc and gnss first specified in this revision. * 9 devices using a
Emergency_communication Identifiers Maritime_communication