A Vessel’s MMSI
The United States Coast Guard indicates that MMSI stands for Maritime Mobile Service Identities, and it is a nine-digit unique number identifier used by AIS tracking systems. Like the Call Sign this is a regulated number and it is done so over in Geneva, Switzerland.
The arrangement of the numbers can be used by users connected to telecommunication services and call ships automatically through VHF Radio.
To view the MMSI number in ShipTracks click on the vessel of interest and the dashboard will open. Click on details and a windowpane with 3 tabs will open. Head over to the AIS Info tab. This tab contains extended information about the vessel’s AIS unit. The MMSI should be the 4th row down.
A Vessels IMO Number
IMO stands for the International Organization Number, this is a unique number which consists of 7 digits.
Unlike the MMSI, the intention for the IMO is not for communication, but to reduce fraud and increase safety.
To find the IMO for a specific vessel in ShipTracks click on the vessel of interest the Dashboard will open displaying a summary of AIS data. The IMO should be found below the vessels name.
The Call Sign
The Call Sign is transmitted through VHF radio alongside the MMSI. This is a unique identifier containing both characters and numbers. The purpose of the Call Sign is to identify vessels, sometimes vessel names may be similar or the same, but the Call Sign helps identify which vessel is which.
Merchant and voluntary vessels are not required to get a Call Sign.
The Call Sign can be found on the ShipTracks Dashboard after clicking on a vessel you’ve searched for. The window pane will open and to rows down you will see the information.
