I always use facetime with my girlfriend using my iphone 4 and never had a problem with it. However, I recently purchased a new iphone 5 and have noticed that facetime always keeps on lagging and most of the times I cannot hear what my girlfriend is saying. But whenever I switch back to my iphone 4 then all these facetime problems don't happen. Is this a common problem among iphone 5 users? and how to fix it?