if applied for online. Postal applications cost £20. AN MMSI number stays with the
vessel for its lifetime. If your radio has an MMSI number registered, you should input this information while completing your licence application. This will carry the existing information over to your new licence. If your vessel doesn’t have an
A Maritime Mobile Service Identity number stays with a vessel for its lifetime.
Advice
Be radio wise T
he communications regulator Ofcom, which oversees services such as broadband and
mobile phones, also manages the radio spectrum used by VHF radios. As the authority for Ship Radio Licences, Ofcom is keen to raise awareness about unique radio identifiers – MMSI numbers – being duplicated when a vessel changes hands. This handy guide explains what an MMSI is, how to get one and what to do when transferring ownership.
What are MMSI numbers? An MMSI is a Maritime Mobile Service Identity – a unique nine-digit number assigned to vessels and maritime radios equipped with Digital Selective Calling (DSC) or Automatic Identification Systems (AIS). It’s used to identify and communicate with ships, coast stations and rescue authorities.
Maritime Mobile Service Identity numbers are vital for safety at sea. Find out how to register and use yours
Why do MMSIs matter? They play a critical role in emergency responses and collision avoidance. Using an incorrect MMSI number is a breach of the terms of a Ship Radio licence, and can lead to losing your licence and even receiving a fine.
How do you get an MMSI from Ofcom? MMSIs are issued by Ofcom as part of the Ship Radio licensing process. There are two types of Ship Radio Licence: the Ship Radio Licence (which covers all radios on a single vessel) and the Ship Portable Radio Licence (one per handheld device, used aboard multiple vessels). Ship Radio Licences can be obtained via Ofcom’s website and are free
MMSI number, you can have a new one generated when you complete your application. Once your licence is processed, your MMSI number will be displayed on the licence document. Ofcom gives these details to
international authorities so that you’re registered for search and rescue operations, should the worst happen.
What to do if you sell your vessel Licences are non-transferable, so if you sell your vessel or radio you must surrender the licence. If this isn’t done, MMSI numbers can become duplicated in Ofcom’s system. This creates a serious potential safety issue, as it affects the ability of rescuers to understand who may need emergency help. Where MMSIs are duplicated, Ofcom will decide who retains the existing MMSI and who requires a new one. It’s important you have the
correct details when applying for a Ship Radio Licence and always follow Ofcom guidance. To apply for a new Ship Radio Licence or add an MMSI to your existing licence, visit
www.ofcom.org.uk/ spectrum/radio-equipment/ships- radio RYA guidance is available at
www.rya.org.uk/knowledge/ regulations/licensing-onboard- electronics
“MMSIs play a critical role in emergency responses and collision avoidance”
rya.org.uk AUTUMN 2025 47
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