Bassman, 179 and some other members and I speculated a few weeks ago about whether there would be interest in setting up a S-B member group MMSI number for VHF DSC calling. DSC-capable VHFs have a group MMSI calling feature with which members of a group (any bunch of boaters whether recreational or commercial who want to talk to each other on the water without others listening) can call the group and automatically shift to a pre-determined channel. With scrambling, it could be a confidential discussion. I finally got around to checking out what would be required to do this.

First, people with DSC-capable VHF units would have to have an MMSI number, which is obtainable from BOATUS, the FCC, and other places. Then, a group is established by people wishing to call one another while underway. DSC-capable VHFs have a data entry routine for entering the group MMSI number agreed to my members of the group, and then apparently it's all automatic after that.

Now, the issue: The USCG site explained that to create a group MMSI number, only one member of the group simply would make a small change in his/her MMSI number, or any other groupmember's MMSI number, to use as the group number. Then all members of the group would enter that number as the group number, and off they would go.

The CG site said you take your FCC-derived MMSI number, all of which have a zero at the end of them as the 9th digit, move the zero from 9th in the series of numbers to the 1st (so, 336123450, for example, would become 033612345), and that would be the group number.

FIRST QUESTION: Does anyone that has an MMSI number have one with a zero on the end of it? Mine has a 7 as the 9th digit; Bassman's is a 9. I got mine from BOATUS.

SECOND Question: Does anyone know how to get one with a zero on the end, and how to replace one without a zero on the end with the new one??????? :confused: :confused:

check my radio to see if it is equiped for this?

I have to be honest, I have never used this feature of the radio. I
I would like to learn more about MMSI and DSC group operation and get it working properly on my radio. You have any good info on this? It sounds like a neat feature...It should be able to pass lat lon info from each others gps device, and from what I read, when I recieve a DCS call it the callers position will pop up on my chart plotter with a heading towards it (if he has it connect to his gps). This might be only for distress calls but I would think you could use it to covertly pass positions.

Lets start with a dumb question... what does MMSI stand for.

i will be interested. Just need to get my vhf registered for dsc. And we will be buying a chartplotter this or next month, so we can even send each other lat and lon#s :rolleyes: :eek:

No matter what, your still limited in distance, just like regular VHF.
But, let us know how it works out.

http://www.marinecomputer.com/articles/mmsi/mmsi.html
Maritime Mobile Service Identity
There is a way for some U.S. users to obtain an MMSI without applying for a license and paying the associated $120 fee. Recreational users who will remain in domestic waters and only carry VHF, EPIRB and Radar are not required to be licensed, but may wish to obtain an MMSI for use with a VHF DSC radio or EPIRB. For these users, the FCC has entered into a cooperative agreement with BOAT/US to assign MMSI numbers and relay registration information to the Coast Guard in the event of a distress call. Registration can be done either on-line at www.boatus.com , or call them at 1-800-563-1536.

Reportedly, marine operator MariTel will soon also be authorized to assign MMSI numbers to domestic, recreational vessels. Contact them at 1-888-627-4835 or check www.emaritel.com for details.

Found my number...ends in a 5.

If I enter a group number, will it effect my personal number? I think I can only change a MMSI number 2X in my radio and then you have to send it back for a factory reset. OR are group numbers different?

Count me in guys....179, pm me how to do this....

I am in and my radio is all set just need to go to Boat us for #

Homerun,
As soon as I figure it out I'll help you, but knowing me it could be awhile :rolleyes:

Sandman: As i understand it, entering a group MMSI number in the part of you radio for doing that, will not affect your personal MMSI number at all.

Everyone: You can get your MMSI number online for free at BOATUS.com.

All that's involved in setting up a "group", is for every member of the group to input the GROUP MMSI number into their radio. It is entered on a screen specifically for group numbers. You don't do anthing to your personal MMSI number to do this. I think, actually, that group members could use any number to set up a group, as long as its first digit is a zero. They just all have to use the same group number for the group DSC funtion of our radios to work. The USCG explanation said that to pick a GROUP MMSI number, all you do is take any personal MMSI number in the group and put a zero in front of it and drop its last digit. So, 336234567, would become a group number of 033623456, and all members would enter 033623456 into their respective radio's group MMSI number set-up.

As I understand it, any radio that is turned on and within range, that has that GROUP MMSI number set up, will respond whenever any radio in the group that also has that group number set up, sends a msg using the group DSC function (DSC is Digital Selective Calling). When a group DSC msg is sent, two things happen: 1. All radios with the group MMSI number will first automatically switch to the channel the sender has selected for his group DSC call, and 2. all members (a "member" is defined as anyone with that specific GROUP MMSI number set up on the radio), can then communicate with each other just as if they were making a conference call on telephones.

So, suppose five S-B members who are using the same S-B GROUP MMSI number are out one day and one of them gets into fish. If he wants to (A BIGGGG ASSUMPTION!!!), he could make a GROUP DSC call and all the other four would automatically switch to that channel and receive his message. The other four could call back and they would all be on the same channel for a certain amount of time. After some delay, if there is no further calling on that channel, all their radios would automatically jump back to the channels they were on when the group DSC call was first made (although I am a little unsure about this part).

I also THINK the call automatically sends lat-long info to all group members, as long as the sender has a GPS NMEA connection and the GPS is turned on.

The DSC funtion of radios is set up to send at least four types of DSC calls: individual, group, all ships and maritel telephone, in addition to the distress calls. Without getting into all of the options, if you selected "individual" for a DSC call, then only that individual's radio would switch to your selected channel. For a group call, all members of the group would automatically jump to that channel. In both cases, the receiving radios would display the caller's lat-long and some other stuff.

Radios have built-in timing protocals for handling DSC messages. Certain things happen, for example, when you make a DSC call and no one in the group is up and operating. Certain time delays go into effect and certain msgs show up on the sender's radio telling him there's no one around, basically, and the radio jumps back to the previous channel.

I think a good idea would be for a group of interested S-B members to identify themselves to each other, and then we'll create a GROUP MMSI number among us. Then each of us will enter that number as our GROUP MMSI number for the GROUP DSC calling feature in our respective radios. Then, whenever we get into the water, we'll just give it a try and see what happens.

Whadyathink?

BTW, I hope everything I've said here is accurate. Obviously, anyone interested in using the GROUP DSC calling feature of their radio should READ THE OWNER'S MANUAL to see how it works.

Now if we only had VHF's that had a 100mi range:rolleyes:

I can only get about 20-25 mi on mine.

I agree with you, Sandman. But, if I got one of these msgs saying that a member is 30 miles away and into fish, I'm not going to head to where he is, not in my little 20-footer!! I'm not even sure I'd do it for 20 or 15 miles away!

So, at least for fishing applications of the DSC function of my radio, 20 miles is fine.

For distress calls, the msg goes to anyone with a DSC station authorization. That usually would include a lot of boats within the radio's ranges. And if the sender selected "all ships" as the DSC sending mode, then every boat with a DSC radio turned on, would get the distress call. In either case, boats could relay the msg to the appropriate people.

I'll join this conversation when I get my new radio with DSC. Anyone know of any killer deals on the little ICOM?

Mike:

I found the best deal I could on-line, and then printed it out and took it to West Marine and got the unit for that price from WM. It worked like a charm. I had to pay the on-line company's shipping charge at WM, but it saved me $125.

People with questions about all this DSC and MMSI stuff can check the following USCG/BOATUS sites for info (this is actually the BOATUS site that one is referred to by the USCG's site):

http://www.boatus.com/mmsi/faq.htm

Check out the navcen link within the list of items when you get into the BOATUS page.

See if you can figure out how a recreational boater would go about converting his MMSI into a GROUP MMSI number.

Well - I finally got my T-top installed and have the VHF with DSC installed. I programmed in my MMSI and the vhf is wired to the GPS - all is working fine.

If anyone is still interested in this issue - I figured out how to get a group mmsi. I wrote to the USCG and they pointed me to this Q&A:

I own a small fleet of boats, each equipped with DSC-equipped VHF radios. I have already programmed each with an individual MMSI number. These radios also allow programming with a vessel group MMSI, which I need for calling all of my vessels. How do I obtain a vessel group MMSI assignment?

Your individual MMSI assigned by the FCC should end in a zero. To obtain a vessel group identity, take any one of your individual MMSI numbers, remove the zero at the end of the number, and add a zero at the beginning. That new number will be your vessel group identity. For example, if your individual identity is 366123450, your vessel group identity is 036612345. If your individual identity does not end in a zero, you will need to obtain a group identity from the FCC or the agency which assigned you your individual identity.

So - it looks like we simply take any one of our MMSI's that end in a zero and switch the numbers - my mmsi 338025379 doesn't end in a zero. Does anybody have one that ends in a zero that they want to use to establish a group mmsi?

Not sure if the DSC thingy ever took off but a few of us have been using VHF channel 69 which seems to work well. Just remember to go to low power when in close range.