What is MMSI?

All modern VHF and MF radios are equipped with Digital Selective Calling (DSC). All DSC equipment is programmed with a unique nine-digit identification number, known as a Maritime Mobile Service Identity or MMSI.

This identity is the DSC contact number for a vessel. The MMSI is sent automatically with each and every DSC transmission made.

A vessel or shore station can use the MMSI number to alert another vessel that they wish to communicate.

DSC acts like a pager which has a short message indicating which radio channel to use for the subsequent radio conversation.

In the case of a Distress DSC call, all DSC equipped radios within range will receive the DSC distress transmission - this is automatically an 'all stations' broadcast.

HM Coastguard MRCCs all have their own unique MMSI number (listed below) so that they can be called directly by boats or ships at sea.