Facetime, WiFi and # of bars question
(So poor that when she called AT&T to discuss if this might change in the future, the service rep said she shouldn't have any service at all where she lives. She'll take the low bars when she should have no bars. But I digress...)
We tried FaceTime yesterday and it worked only so-so.
Here's my question: when a voice call is switched to video chat, is the call actually jumping from the phone service to the wifi network? And if this is so, then shouldn't the reception be phenomenal via Facetime? Isn't the AT&T network (and the no/low bars) being removed from the equation?
Thanks for any feedback on this.