Even the NA-optimized version does not work reliably with AT&T or Verizon. The fact that the Mudita Kompakt has not been registered as a supported device leads to a number of issues. It seems like T-Mobile will be the way to go (though I personally haven’t tried it, I’m just going off reports here).
Details of my saga here in case that helps: Mudita Kompakt does not work with AT&T