What is the purpose of DSC in GMDSS, and what information does it convey?

• A. Digital selective calling sends distress, safety, and calling messages with MMSI numbers to designated stations.
• B. DSC is used only for routine weather updates.
• C. DSC stores last 24 hours of log entries.
• D. DSC encrypts messages for security.

Answer: (A)

DSC in GMDSS is all about fast, targeted signaling. It provides automated digital calls to specific stations using Maritime Mobile Service Identities (MMSI). This system is designed to send distress, safety, and calling messages so that the right vessel or shore station is alerted immediately, even when voice channels are noisy or congested. The information carried by a DSC call includes the type of message (distress, safety, or routine), the MMSI of the originator, the MMSI of the intended recipient, and often additional data such as position and time to help responders know where and when the alert was issued. Because DSC can trigger automatic monitoring and acknowledgement workflows, it greatly speeds up initial contact and coordination at the onset of an incident. It’s not used for routine weather updates, it does not serve as a log storage system, and it does not provide encryption for messages.