We have several (old) MDAs and all are using V.110 to dial in to our router. The first MDA II now uses V.32 modem connections regardless what I configure as CSD line type.
ROM version of the MDA II device is 1.03.00 GER. I haven't tried 1.60 yet.
I asked T-Mobile but they have no idea what's happening there. It "should" work...
I found other postings (not here) with the same issue. But no answers.