Got my iPad mini in early Feb and signed up for the 250mb data plan. On Feb 17th I was in Chattanooga TN and made a successful FaceTime call to my daughter in Atlanta over my cellular connection. On February 19th, I upgraded to the 3gb data plan. Today I attempted to make a cellular FaceTime call, but a pop-up tells me I need to be on wifi or an eligible data plan.
Did something change with AT&T in the last two weeks? The iPad is the only AT&T device I have. How come my 250mb plan allowed it two weeks ago, but my more expensive 3gb plan doesn't now?