I am having the same issue with calls, as well as an intermittent problem with my media volume control. Sometimes it says that it is muted by showing an x symbol over the speaker symbol, but just for the media. The odd part is that the volume bar for my media will say that it is turned all the way up. When I try to turn it up using the volume rocker on the side, it won't let me, it stays in one place. I called tmobile and asked them if this was a common problem, and before finishing telling them what is going on, they just told me to bring it in, and exchange it for a new One. I am not sure that I am going to waste my time now that it seems like it is a software problem and not a hardware problem. Any thoughts?