I have iOS 9.0.2 , just could activate vowifi with Att. It is not like t-mobile, always avaiable, it is only when you are in low/no network zone. To verify how it is work you can "force" it on your iPhone : 1. switch on airplane mode, 2. turn on wifi You phone will think that there is no cell network and att vowifi symbol appear right away. Just made my first call, great quality. Interesting, if I use outside the US with US proxy? What do you think?