cannot make calls or send message with tmobile in italy

Why no t-mobile support in Italy The t-mobile app does not open. The t-mobile cellular partner WindTRE does not want to help with issue. 

I have roaming turn on and it works great with google maps and chrome. Apparently the t mobile network is grayed out and the chosen cellular partner does not coexist with t mobile in italy.  

Do you have roaming enabled on your device?  Does your plan include roaming?  Is your device compatible with the roaming partners network?