There are two reasons why you need the MMSI code.
1. In Singapore, you need to apply with IDA for any marine radio devices.
2. For identification.
Will it work without MMSI? Yes, it does.
The MMSI is what makes the Red button work, the only difference is that if it is used outside of Singapore Water, it will not provide them the personís name and information. But it will provide them the GPS location of where the person is and a digital distress signal.
Please make sure that everytime you use your LifeLine, to make sure they plug it in the computer and with the desktop software open and change to the appropriate region.
I have tried but still don't know how to register for MMSI, I went through the IDA website, the form for applying MMSI is only cater to boat owner, I don't see any application for radio devices.
Secondly, without programing the MMSI, all the other functions works except for the red distress button. Was tempted to use my boat MMSI but on second tough, better don't do that because what if one day I bring this unit go diving elsewhere and really drifted and need to press the red button, rescuer may think my boat sink and activate a big boat to come and rescue.
Just for discussion sake, what do you think if I just enter any random number like 123456789? As long as this is not a number belongs to a boat, and the red distress button works, if sua sua I need to activate this button and need rescue, as long as I am rescued, they can scold me or give me a fine, it is ok! Most important, I can be rescued.
is there a region setting? I don't notice that. My understanding is that as long as the voice channel is set to the same as the boat that you are diving with will do?