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VHF DSC radio - MMSI number - Transport Canada

If you've recently purchased a new VHF marine radio for your boat, it is probably equipped with a Digital Selective Calling (DSC) feature that allows selective calling on VHF Ch70.

What is the MMSI number on boats?

To make a digital call each radio must have an identity, a 9-digit Maritime Mobile Service Identity (MMSI) number. Your owner's manual will tell you more about this feature and how to make a DSC call to another boat or to a shore station that has DSC capability. MMSI numbers are assigned, free of charge, by Industry Canada.


One important feature of a VHF DSC radio is that it can also send a Distress Alert which will tell the Coast Guard and other boaters in your area that you require immediate assistance*.

*Where VHF/DSC services are available. For more information, please contact your local Marine Communications and Traffic Services (MCTS) Centre.

As well, if your boat is equipped with a GPS receiver, it is highly recommended that it be connected to your DSC radio. This will ensure that your position is automatically sent when a ¢ is transmitted. Rescuers will then immediately know your exact location and assistance will arrive sooner.

Warning: DO NOT TEST this Distress Alerting feature, there is no test feature, and in fact it is an offence under both the Canada Shipping Act and the Radio communication Act to send a false distress message.

Just imagine the scene: you're out cruising with your family in your boat, when you suddenly smell smoke. You immediately stop the engine, and grab a fire extinguisher and check it out. You discover that the whole engine compartment is on fire!

The cabin is filling with deadly smoke, and you don't have enough time to get a mayday call out, but you do have time enough to hold the Distress Key on your radio down for 5 seconds, before you and your family abandon ship. A Distress Alert has been automatically transmitted on Ch70, clearly identifying you by the MMSI number, and your location, thanks to the GPS.

The call is received by the Coast Guard, who immediately send out the appropriate rescue resources*.

*Where VHF/DSC services are available. For more information, please contact your local Marine Communications and Traffic Services (MCTS) Centre.

All you had to do is hold the Distress Button in for 5 seconds and help was on the way! This feature is only enabled on those radios that have been assigned a MMSI number.

The Coast Guard urges you to complete an MMSI application form available from Industry Canada. Contact the Industry Canada District Office nearest you for more information.

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