Change MMSI number ? simrad rd 68 - Simrad RD68F VHF Radio Class D DSC by GPS Receiver

This is the official line

Can I change the MMSI number entered into a VHF radio or AIS unit?
Once entered and confirmed, the MMSI number can only be changed by a certified technical dealer. If you need your number reset or changed, it is recommended that you contact the organization or agency which originally registered your MMSI. For more information about MMSI numbers, go to the United States Coast Guard website at this link.

And

https://www.justanswer.com/boat/au99m-received-emailed-info-from-simrad-reset.html

This doesn't sound hopeful!

https://mt.panbo.com/2015/07/simrad-ai50-mmsi-reset.html

Full story

https://www.google.com/search?q=reset+Simrad+AI50+ais+to+a+new+MMSI

..

see this link https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwir2KrP2ariAhWF3KQKHcoWCB0QFjAAegQIBRAB&url=http%3A%2F%2Fwww.cruisersforum.com%2Fforums%2Ff13%2Fraymarine-ais650-change-mmsi-number-165250.html&usg=AOvVaw0xeJI7BY3QB68BYDGrh-1U

You cant. Contact previous owner and ask for mmsi transfer or contact manufacturer about how to program new mmsi number.

here
https://www.boatus.com/MMSI/MMSI/ObtainMMSI#!

from the marine authority in your country ?
if you were from the usa it is
https://www.boatus.com/mmsi

However I don't know which part of earth you do your boating in ?
google search mmsi and add the country you are from ?????

Boat US MIGHT be able to tell you since they were involved with MMSI numbers If not try the USCG

Has it ever been setup for a MMSI? If so, I think they can only be set once and need to be cleared by the factory to be ready for a "new" MMSI to be entered.

Hi Peter!
NICE radio Man. You're right, Uniden customer service is horrible.
Ok, here's the deal. You HAVE to get this right the first time, otherwise you pretty much have to send the unit back to Uniden.

Press and hold CALL until the setup menu appears.
Press ENT (1W/25W), that gets you to the user MMSI portion of the program.
NEW should be what you see on the screen.
Press ENT. That'll get you to where you actually get to enter your number.
Using channel up or channel down, set the first number.
ENT
The cursor moves to the next digit.
Repeat until your full MMSI number is entered and displayed on the screen.
IF YOU MAKE AN ERROR, don't panic, press clr/scan and the cursor will move back one spot to the left, erasing the wrong digit.
When the ninth digit is correct, press ENT. The screen will display your MMSI number and ask you to confirm. To save, select yes. To cancel, select no.
Before saving the number, your radio will ask one more time if you wish to confirm and warn you that this is a permanent setting.
Press ENT to confirm, or CLR to start over again.

Hope this helps.
-Steve

I don't think the RAY100 is DSC compatible and therefore doesn't have the MMSI programmed into it. Most manufacturers limited the number of times that the MMSI can be programmed to one (!). After that, it has to got the factory or to an authorized dealer who can bypass the restriction.

This is not a motorcycle problem but a Marine VHF radio problem!