The Panbo Forum

Return to Panbo Forum main page »

Tim Flanagan

Group MMSIs: Any use at all?

Vote 3 Votes
I remain faithful to the idea that Group MMSI numbers OUGHT to allow vessel fleets, particularly recreational boaters, to communicate more easily. Yet I NEVER hear about them being used. What's the deal?
It came up because of a comment I received on this Navagear item: MMSI Confusion: Group MMSI Numbers?  I figured the reader probably wasn't the only person with this type of question, so I posted a follow-up: MMSI Confusion: Group MMSI Numbers Redux.
The issues raised in both of those posts got me thinking, though: what's the dang problem?! Partly, I suspect, the available user interfaces tend to discourage using DSC for anything other than distress hailing. On top of that, the coordination required among the "fleet" requires a bit more effort than most recreational (fishing, racing, cruising) fleets are probably willing to do. Are those two factors enough to effectively kill Group MMSI functionality? Or is there more to it?

22 Replies

  • I've yet to find anyone even using DSC for a point to point call. When I raise the question, most people haven't bothered to even give it a try, they still hail away on 16 hoping to connect.

    I lay the blame on the radio user interfaces for DSC; they are positively stone age. They were done by the same guy who designed the clock setting feature on VCRs! Is there a radio manufacturer who has ever heard the term "user interface" design?

    Big opportunity here for someone.

    Group MMSI, not going to happen until the UI gets fixed.

  • It's a shame too, because point to point DSC calling works well in my experience. But my experience is almost entirely calling one test VHF from another! I agree that the UIs could use a lot of improvement, but another part of the problem is that most of us have too many UIs rattling around our brains.

    As for Group MMSI calling, I recently got excited when the USCG clarified how a person can create a Group MMSI that could be used by a cruising group or yacht club or whatever. It's explained here:

    "No process currently exists to assign non-federal group ship station identities. However, users having an MMSI assigned by FCC license, all of which have a trailing zero, may create a group identity by inserting a zero before the identity and removing the trailing zero (e.g. a user having an MMSI of 366123450 is allowed to use the group identity 036612345)."

    BUT there's a significant glitch. Those instructions only apply to FCC assigned MMSI numbers. MMSI numbers distributed by BoatUS, Sea Tow, etc. do NOT end with a trailing zero, and even the USCG doesn't know how to make a unique group MMSI from one! I got discouraged but will pick up the research again one day...

  • I lay the entire blame on the user interface not just once, but twice, in that to succeed not only did it have to be better than it is, but it also needed to evolve in the face of competitors and it failed to do that also. The UI needed to be competitive for acceptance by users over the alternatives ...

    By that I mean it's failure lies in it's inability to compete against cell phones which are (mistakenly) believed to be highly effective on the water with a user interface we already have, not just for dialing numbers, but effective at having memories that already contain the numbers of people we wish to reach on the water.

    DSC even fails to compete against the alternative of just using channel 16 or a VHF channel where a traveling fleet of boats pre-arranges to monitor. People know how to do that, and will continue to believe it’s good enough vs. the effort of getting everyone in the fleet to learn and use the DSC feature. What on earth did the designers of DSC have in mind!! Imagine cell phones having a 2nd dialing method (like DSC is to channel 16), where you had to follow multiple keystrokes only learnable in your user manual, and hard to remember! No matter what the benefit of that 2nd method, people just wouldn’t use that on a cell phone. CASE IN POINT was the earliest of integrated address books on cell phones; they went unused by 97% of users. That UI evolved, where DSC has not, in that the evolved 2nd method for dialing on a cell phone … what we have today where (without reading a manual) you can click on someone who just called you and add them to your address book with the name of the caller (thank you caller ID) has made integrated address books successful on a cell phone.

    Maybe with AIS that caller ID function from cellphones can start to exist in DSC (I can’t think how exactly). Then again … that might not be enough, in addition to an evolution of the UI, some other evolution may need to happen to the underlying standards and a killer application to utilize it be invented.

    One thing the inventors of DSC did get right, was the tie into Rescue 21. By including this SAR capability … at least the inventors of DSC have given a motivation for almost every boater to obtain and program an MMSI number in their radios … step 1 for them even being DSC callable. Or maybe not … my current efforts to get the 85 members of my cruising club to get their boats Rescue 21 capable … has been slow. Probably a member is more likely to have their VCR clock programmed with the time, than their VHF radio with MMSI, even as we begin our second season with Rescue 21 on Long Island Sound.

    Personally, as I wrote in Tim’s blog, rather than see some great integration of DSC calling and AIS … I would much rather see AIS evolve to show the VHF channel my AIS target is currently listening too and forget DSC calling altogether. So if AIS showed boat name “69 Comfortably Numb” as the boat name .. I could pick up any VHF radio in front of me, dial up 69, and just hail them verbaly ... like VHF radios were originally designed to do.

  • I don't expect this problem to be solved by the VHF. Looking at the Lowrance LVR-880 and the Garmin VHF 200 as examples, there just isn't enough screen real estate and button bandwidth to handle DSC. No one is going to come out with an iPhone like intuitive VHF interface.

    I do expect this to happen with the N2K chartplotters (and N2K AIS!) and since Garmin makes both chartplotters and VHFs, I won't be surprised to see them do it first. I can imagine having *less* of an interface on the VHF, back to old school minimalism, and rely on the chartplotter for the DSC stuff. With the 4208 not having a GPS and the AIS500 not having an interface, we're naturally headed in that direction already.

    Lastly, it would be nice if all of the manufacturers listed their supported PGNs in their documentation. Maretron does this.

  • Bingo, Olsonist! I totally agree. The MFD should be at least the alternate interface to complex DSC stuff. One button calling AIS targets, adding AIS targets and incoming DSC callers as buddies whose targets are marked when in range, or polled on command...

    The Standard Horizon CVP plotter/VHF already does some of this stuff, and it's so much easier with knobs and softkeys and plenty of screen room for prompts, etc. But I'm fairly sure it can be done using N2K networking, and wouldn't even require the same manufacturer's radio and MFD...

    Assuming that the needed Standard 2000 PGNs are in place, which I'm not at all sure of. Heck, I learned in Miami that the PGN for the Class B static ship data message is just getting finished, and that message was created several years ago. Doh!

    At any rate, I'm convinced that good MFD/AIS/VHF integration will be good for DSC usage and good for the manufacturers who make it happen.

  • I proposed a group ID to my sailing club, with 170 boats. We list mmsi's in the club database, and there are a whopping even dozen boats that have MMSI's and a few of them are bound to have SC-101-only radios. So far, its a problem of getting more boats to update their radios. This summer will tell.

  • Dan's right, the User Interface was written by the same engineer that described setting up my first fax/answering machine. I think he can be found at Dante's fifth ring of Hell. Until and unless MFD's all have radios built in (Hats off to SH) some protocol is needed to coordinate call lists between the GPS and the VHF, or we will be stuck keying in a nine digit number in times of elevated stress. NMEA is the logical candidate, but I can't help but wonder if we are pushing the limits on current processors

    While helping other people set up their DSC, I discovered that there is commonality among the twenty-something pages of DSC instructions from several manufacturers. How did that happen? Is it a result of some convention?

  • One of the major problems is that regulatory and industry acceptance delays any hope of integrating new technology into the marine environment.

    I recently interviewed the USCG ADM in charge of Acquisitions and, while I was genuinely impressed by the Rescue 21 initiative, I found a few limitations which I posed as questions (answers are in parenthesis):

    1) Everything is point to point. If I am 500NM out and have contact with a cutter that's equipped with a 24/7 sat system, is my call routed to Rescue21 or does my message need to get relayed? (relayed)

    2) When the Cosco Busan allided with the SF Bay Bridge 7 pilots decided to remain in port while one decided to get underway. Are you developing any systems that would allow real time communication between vessels. (He said VHF works but acknowledged that you wouldn't want to have that discussion on a public channel)

    3) Why can't we have a system that allows everyone in the port to log-in to share data, view problems and "conference call" or chat in real time? (We'll have Marine Safety look into it).

    When Marine Safety called I told them that with a simple 3g data card, external antenna and Cradlepoint router I can access all of the tools of the internet from 90% of the harbour. Let's fund redundant (and secure?) 3g networks and integrate it into marine electronics and the ECS programs being used by pilots (like rose point navigations).

    Anyway, this is certainly a topic that interests me and could bring new functionality to the (currently useless) group MMSI numbers of GMDSS.

    As far as DSC, it works well and I used it aboard ship on a daily basis. Simply pull the MMSI number off the AIS then input it into the VHF and suddenly you are talking point to point!

  • On the two VHF radios I use the most (Icom M601 and Standard Horizon HX850S) programming MMSI data in is straightforward and does not require consulting the manual. I have one group MMSI programmed into both (analogous to the address book of a cell phone) that works nicely although it doesn't get used often.

    My principal use of DSC is between my boat (the Icom) and dinghy (the SH), although I also use it in cruiser-heavy anchorages as a way for friends to reach me without me having to listen to the garbage on the "cruiser channel" (VHF 68 around here).

  • PROGRESS! Something lit a fire under the Skippers in my club. There is a flurry of emails about what radios work and how to wire them, and (at this moment) what we should use as a group ID.
    Do we all think that a private organization need use the MID sequence in their group number?

  • Cool! Sandy, as discussed above, I think you just need one member with an FCC assigned MMSI (that ends with a zero). Move the zero to the front, and you'll have a Group MMSI that all members can program into their radios (if possible) and use to make group DSC calls.

    The whole idea with the zero shifting is to create a group MMSI that does not duplicate anyone else's regular or group MMSI. Please tell us how this works out.

  • I just activated the MMSI number in a Uniden Oceanus
    VHF/DSC radio.

    I don't have the manual.

    How do I make my first call to ANOTHER dsc EQUIPPED vessel if I know their MMSI Number.


  • Stepphen, looks like your manual is downloadable here:

    You need to go Menu/Setup/Directory and enter your friend's MMSI. See page 33.

    Then go MENU/DSC/Individual Call, explained on page 21.

  • I am organizing a group of boats for a trip. The lead boat has an MMSI number assigned by the FCC so the last number ends in 0. I have some questions about using a Group MMSI.

    How does the lead boat establish/create the Group MMSI? Does he just have the other boats program the Group MMSI number (made up of adding a 0 to the front of his MMSI and shifting the rest over and dropping the 0 at the end) into their VHF's?

    If the lead boat calls out to that Group MMSI number does it pass through to each boat's VHF that has that number programmed at the same time?

    After making the Group MMSI call out will all the boats that have that number programmed into their VHF be on the air at the same time like a party channel?

    If the lead boat calls the Group MMSI number on VHF channel 68 for example will the receiving boats VHF's switch to 68 automatically?

    If any boat with the Group MMSI number programed into their VHF calls out to the Group MMSI number will everyone be contacted including the lead boat?

    Can it really be that simple?

    Note: The trip will be made up of a mix of US & Canadian boats all with their own MMSI numbers

  • Warmrain, I think it is pretty much that simple. But don't count on every boat's VHF automatically changing to the working channel chosen for the group call. Some radios can be set up to that, but most seem to require some human intervention, as in a screen like "To switch to 68, press Enter".

    I've never experimented with group calling, but I think you'll find that any radio can place a group call. Please report back on how it goes, perhaps writing up a Panbo guest entry on the subject. Thanks.

  • Ben wrote:
    ......Some radios can be set up to that, but most seem to require some human intervention, as in a screen like "To switch to 68, press Enter".....
    I am teaching SRC courses with ICOM
    SRC Kurs
    and there is a automatic change to the working channel when the called skipper "is able to comply".
    If the called skipper has the choice to stay on 16 then the two boats will not come together.
    Are there really a lot of DSC radio where the called skiper has the choice to select the working channel?
    Thanks. Wilhelm

  • I believe there are more serious issues than this, such as the DSC feature being turned off by default from ICOM.

    When I was last in Maine Ben attempted to make a DSC call to my ICOM radio. Even thought I was expecting the call, I could not receive it.

    I would later discover the "DSC Watch" is DEFAULT to OFF on ICOM-M304 radios (the radio packaged with Beneteau sailboats for years).

    See page 30 in the ICOM manual, DSC Watch

  • Re older ICOM radios and the DSC monitoring being set to OFF:

    I found that to be true on my ICOM IC-M402 radio. I had been using it for years. I had no idea it was not paying any attention to DSC calls. For more on this see

    ICOM IC-M402: Rehabilitating an older VHF Marine Band radio

  • Hi,

    I have three fixed VHF radios on board. They are all DSC capable Icoms.

    I am yet to make or receive my first DSC call.

    The rules say (I cannot remember whose rules - sorry) that each and every radio should have the same MMSI loaded into it, and I have done that.

    Can someone tell me what happens when I receive a DSC call?

    Will all three automatically switch to the DSC channel and leave me monitoring nothing else?

  • Mike, in my experience you can place DSC calls between radios that have the same MMSI. I've done it with several brands. It's good way to see how DSC works, in case you get a real DSC call some day ;-)

    Also, I think you'll find that your radios can be set up to respond to DSC calls in different ways. It depends somewhat on model, but they don't usually change channels automatically unless you set them to.

  • Hallo Mike,
    the DSC radios have a independent watch receiver only listening on CH 70 all the time.
    When a DSC call is received,
    than all 3 should change to CH 16.
    If you would like to have one or two of the radios to stay on their channels other than 16,
    1. you might delete the MMSI so the radio will not be adressed.
    This was possible before 2003 with some modells.
    Today you have to enter the MMSI first to use the radio even for a voice call.
    2. You might look into the SetUp mode if there is a switch that you can set the DSC off.
    Greetings, Wilhelm
    SRC Training

  • I agree it would be good to have a directory of marine DSC group numbers. I agree so much, I started a new website about this subject and a very high focus is a "clearing house" of Group numbers. Please click below, and be sure to click on "Known Groups".