mobile

I had it unlocked and was using a T-Mobile sim card, I dial the number and it looks like it will make the call but it doesn't go through. Same thing happened if I try to receive a call it doesn't go through. I already re-flashed the CP NC2 for this model and it didn't do anything. I have z3x box that I just got, is there anything I can do to fix this issue? It does find the T-Mobile network on manual search but doesn't have an effect on the tuning. I also show a line of signal. Thanks in advance guys.