MMSI Numbers Flashcards

What is the MMSI format for a life-saving appliance (e.g., EPIRB or life raft)?

Answer: 97XXXXXXXX (10 digits starting with 97)

MMSIs for life-saving appliances such as EPIRBs and SARTs use a 10-digit format beginning with 97, distinguishing them from vessel MMSIs (9 digits) and coast station MMSIs.

What does a group MMSI allow?

Answer: A fleet manager to call multiple vessels simultaneously

A group MMSI allows fleet operators to make a single DSC call that is received by all vessels sharing that group MMSI, enabling simultaneous contact with an entire fleet rather than individual calls.

What is the all-ships MMSI used for DSC all-ships calls?

Answer: 999999999

The all-ships MMSI is 999999999 (nine nines). Using this MMSI in a DSC call transmits to all vessels within range, similar to an all-ships broadcast on Channel 16.

Should an MMSI be programmed into a VHF radio before or after purchase?

Answer: Before use — it must be programmed before the radio is operated

The MMSI must be programmed into the DSC radio before the radio is used. Operating a DSC radio without a programmed MMSI means it cannot function correctly for distress alerting or DSC calls.

What happens if two vessels share the same MMSI?

Answer: DSC calls and distress alerts become unreliable and coast stations cannot identify the correct vessel

If two vessels share an MMSI, any DSC distress alert will identify the wrong vessel to rescuers, creating potentially fatal confusion. Coast station databases will show incorrect vessel details, seriously compromising SAR effectiveness.

Can a hand-held DSC VHF radio have a different MMSI to the fixed radio on the same vessel?

Answer: Yes, each DSC radio requires its own registered MMSI

Each DSC-capable radio requires its own registered MMSI. A vessel may have multiple DSC radios (fixed and hand-held) each with different MMSIs, all of which should be registered with Ofcom.