Long Range Certificate Course

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 as well as MF/HF 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 its 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 DSC radio and could be called by any vessels DSC radio.

The MMSI is programmed into the DSC radio. The MMSI number assigned to the vessel must be programmed by the DSC radio supplier.

Before a new VHF DSC and/or MF/HF 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 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 DSC radio supplier.
  

For ship stations the first three digits are known as the MID (Maritime Identification Digit) number and indicate nationality, e.g. MIDs allocated to United Kingdom are 232,233,234 and 235. The last six digits uniquely identify the individual vessel.

MID xxxxxx

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.

For a SAR aircraft fitted with DSC the first three digits of the MMSI number, followed by the 3 digit MID nationality indicator. The last three digits uniquely identify the individual aircraft.

111 MID xxx

For example, Polish SAR aircraft MMSI number 111 261 123.