MMSI Structures And DSC Call Types

An MMSI is a nine-digit digital identity. The three Maritime Identification Digits (MID) identify the administration or geographical allocation. A ship station identity normally begins with its MID; a coast station identity begins 00 followed by the MID; a group ship-station identity begins 0 followed by the MID. Read all nine digits individually and select identities from the set directory or a current official source.

DSC call types include distress, All Ships, group, and individual calls. Priorities include distress, urgency, safety, and routine. A call type defines who is alerted; priority defines why. Do not use an All Ships call when an appropriate individual call will do, and never use distress priority for routine contact.