A Maritime Mobile Service Identity (MMSI) is a unique 9 digit number and acts in the same way as a telephone number. The MMSI allows radio operator to make automatic calls through VHF DSC radio and is the identity that is automatically transmitted within DSC calls.
These MMSI numbers are issued by the appropriate authorities in the country of registration of the vessel and can be referenced back to a database of information about the vessel and it’s owners and so forth. So, the MMSI belongs to the vessel. Also CRSs (Coast Radio Stations) have their own MMSI because they have their own VHF DSC radio and could be called by any vessels VHF DSC radio.
Before a new VHF DSC radio could be used on a vessel, the following procedure must be taken:
- If a vessel already has its own MMSI number, then its MMSI number should be programmed by an authorized VHF DSC radio supplier.
- If a vessel doesn't have its own MMSI number, then the vessel owner must apply for a MMSI number at appropriate authorities and when the MMSI number is assigned, it should be programmed by an authorized VHF DSC radio supplier.
For example, Cunard Lines Queen Mary 2 MMSI number 235 762000.For CRS (Coast Radios Stations) the first two digits of the MMSI number are always 00, followed by the 3 digit MID nationality indicator, followed by the individual station number.
00 MID xxxx
For example, Palermo Italy MMSI number 00 247 0002.
For a group of stations the first digit of the MMSI number is always 0, followed by the 3 digit MID nationality indicator, followed by the group station number. Group MMSIs are usually acquired by companies for their fleet, or by category of operation or by nationality. The group MMSI is an additional MMSI to the MMSI of a vessel (ship station) and it is used to call all vessels with the same group MMSI with only one call.
0 MID xxxxx
For example, the UK Royal National Lifeboat Group (RNLI) MMSI number 0 232 00002.