One MMSI For All?

Ben Hatheway of Coos Bay, Oregon, asks:

“The VHF and SSB radios on my boat share the same Maritime Mobile Service Identity number. I recently purchased a new marine VHF handheld with DSC capability, and I’m wondering if my new handheld, which is sometimes off the boat, should have a different MMSI number.”

Gordon West replies:

This very important question is now being studied by the Radio Technical Commission for Maritime Services ( and by Global Marine Distress Safety System (GMDSS) special committees on VHF-FM handheld radios. Indications are that a new handheld class of DSC radios, Class H, will soon be created, and that these should have unique MMSI numbers that identify them as portable radios. Since your new radio can send a distress signal, it could be important for the nearest Rescue Coordination Center (RCC) to know it is a handheld transmitter with limited battery capacity and power output, and that it may not be on or even associated with any particular vessel. Given these circumstances, I recommend you seek an alternate MMSI number for your new radio.

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