No, I've ported out of Tata when Tata closed its postpaid service here in rest of West Bengal circle.
From my experience, I feel the problem is of Tata only. With 1X, data often overrides voice. That's why a caller gets busy tone. EvDO shouldn't have this problem. But I don't know, anything can happen with Tata. I used to use hTc Touch 6900 on which strange thing used to happen. While I used to dial a number, it would let me hear the called person's voice even if it was yet to be connected. This was an advantage that while ringing I could hear many secret things. After many months of this enjoyment, Tata stopped this free service to me.