MMSI Numbers Demystified
By Dan Piltch, Marine Computer Systems
US Federal MMSI Numbers
MMSI numbers came into common usage with the availability of DSC (digital selective calling) radios. MMSI stands for Maritime Mobile Service Identity – the scheme managed by the International Telecommunications Union (ITU) in Geneva, Switzerland. Here’s how it works: each vessel applies for an MMSI number that is unique to that vessel. The same number is shared by all radios on board. Acting somewhat like a phone number, the MMSI can be used to “call” a specific vessel (or even a group of vessels).
One of the motivating factors behind the creation of the MMSI system was to allow watchstanders to ignore most of the idle radio chit-chat, but be alerted when a message is intended for their own vessel. (By default, all distress messages are sent to ALL vessels.) When a radio call encoded with your MMSI is received, your radio will sound a special tone to alert you to an incoming message (much like phone rings to alert you to an incoming call).
Anatomy of an MMSI Number
There are four types of MMSI numbers, each intended for a certain purpose. The types are assigned to one of the following:
An individual vessel (ship station identity)
The first few digits of the MMSI can tell you what type of station you’re calling. An individual vessel’s MMSI will start with the MID. So, in the US, a boat’s MMSI number looks like this: 366XXXXXX
If, on the other hand, you have an MMSI for a group of vessels, you’d expect to see a number that looks like this: 0366XXXXX. Note the leading zero – which indicates a ship group number.
Coast stations have two leading zeros before the MID, so they look like this: 00366XXXX.
In each case, the 366 would get replaced by another code for any non-US vessels or coast stations. And the XXX’s indicate the unique identifier for that particular station (or group of stations).
US Federal MMSI Numbers
In the US, any MMSI assigned to the federal government will usually have a 9 as the first digit of the unique identifier, giving a number like this: 3669XXXXX
Using all 9s for the unique identifier will get you the US Coast Guard. So 036699999 would be used to reach all the Coast Guard’s vessels (group ship station), and 003669999 would reach all (or any) of the Coast Guard’s land based stations.
MMSI Cheat Sheet
Here’s a little cheat sheet that might be handy to carry aboard:
MMSI Number or Pattern Meaning
In the US our MID is 366 (367, 368, 369 may also be used).
How do I get an MMSI Number?
While ITU maintains the worldwide master list of MMSI assignments, in the US the numbers are given out by the FCC (and SeaTow and Boat US for some boats). If you’re traveling abroad (beyond just US waters), you’ll need to apply to the FCC. Otherwise (if you’re staying within US waters) you can get your MMSI from BoatUS or SeaTow.
When applying to the FCC, you can get your MMSI at the same time as your radio license and call sign. For this you’ll need to fill out:
You can actually fill all of these forms out on the FCC’s website at https://wireless2.fcc.gov/UlsEntry/licManager/login.jsp?key= Note that you’ll need to register with the FCC and obtain a registration (CORES/FRS) number before you can fill out the forms. Once you’re logged in you’ll want to access the Universal Licensing System (ULS) and begin your application for a ship station license.
If you’re staying within US waters, you can get an MMSI from BoatUS http://www.boatus.com/mmsi/ or SeaTow http://www.seatow.com/boatingsafety/mmsiinfo.htm. Note that these numbers are not registered with the ITU, so if you are in distress with your vessel in another country, the local rescue authorities won’t be able to look up your details when your call comes in.
If you have an FCC-issued MMSI, you can look up your vessel (and anyone else’s vessl as well) in the ITU’s database at http://www.itu.int/cgi-bin/htsh/mars/ship_search.sh
US Coast Guard information on MMSI numbers -- very informative! http://www.navcen.uscg.gov/marcomms/Gmdss/mmsi.htm