This is why I hate apple sometimes too. I changed FaceTime on over cellular in my setting when there was this window a couple of months ago. I had use it on LTE a couple of times and it worked perfectly. Well I updated my iPhone to 6.1 and guess what it changed back to off and want go back on. I have a real problem with apple working with AT&T to screw over customers. A couple of groups a few months back went to the FCC and protested against the fact that AT&T was not letting unlimited users use FaceTime over cellular, but the people that had limited plans could. I guess to smooth things over there was a day or two in dec that AT&T let unlimited customers turn it on. I have kept mine on until today when I guess apple and AT&T got together to stop it. Apple can kiss my butt just as much as AT&T can. They both suck!