How do I reset the mmsi number on my MHS235 radio

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

..

Raymarine Ray55 Manuals Down Load user manual and reset MMSI according instructions.

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#!

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.

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.

Hi,

You've not given much info here, we need not only the Make (Icom), but the Model No. as well to be able to assist you. Could you pls re-post all details of your radio, so that we can follow up on your query.

Cheers, Peter@FixYa Team

This secret code is for the Raytheon / Raymarine RAY 220 VHF. It may work on other Raytheon/Raymarine radios also.

Here you go:

With the Power OFF, Press and HOLD the FUNC, 16/9 and DSC keys while you power ON. Do not release the keys until you hear the audio BEEP which means your done. Then reprogam your NMSI number as per the manual. Pretty easy, hey?

Did you ever solve this problem. I have just purchased a little Leisure 17-SL with a fairly new one of theses radios. I have the handbook and discover you can only program the MMSI once and then return to a dealer to clear it!
Many thanks
Steve http://www.withamweather.co.uk

only a Raymarine dealer can delate the MMSI number with a Sofware