|DSC is basically
a calling system. Each call consists of a "packet" of digitised
information of one of four priorities: Distress, urgency, Safety or Routine.
Messages can be routed to "All Stations", to an individual station
or to a group of stations, using their Maritime Mobile Selective-call
Identity code (MMSI). Distress messages are automatically broadcast to
In addition to the MMSI of source and destination stations, information can be conveyed in the DSC message. For example, to aid the Rescue Services, the DSC Distress alert message is configured to contain the following: