I upgraded to Windows 10 from Windows 7 Professional 32bit. The PC is just about 5 years old and I'm still using one of the first generation MagicJack devices (and yes I mean the ones from way back when the As Seen on TV ads were still running
Ok, so first things first, I had already been using MSC prior to the OS upgrade and it was working fabulously. However given the age of the PC (and my MagicJack) I figured I'd better test it's functionality in Win10 in case I had to replace something. I used MSC to uninstall the Windows service after which the UI launched automatically and the auto-update executed. The update completed successfully and I was able to use the phone to both call out and receive calls without issue. I was also able to successfully send and receive faxes using the HP Fax Back system. I noticed Caller ID didn't appear to be working but I believe that is unrelated to the topic here. I then launched MSC and used it to install the Windows Service again. The UI disappeared and the Windows service was up and active. I then confirmed that I could still call and receive calls and faxes.
Based upon my very limited testing it looks like MSC v2.3 will work to set MJ as a service in Windows 10. However I cannot confirm that this will work with every system and MagicJack device. My post assumes all necessary hardware and its associated drivers/software (i.e. Fax Modem, Multifunction Device, MS Fax, etc.) have already been installed and configured. Individual results may very and are the sole responsibility of the individual following what's documented in this post.
Hope it helps!