This seems to happen quite often. I'll be in the middle of a phone call and the person on the other end won't be able to hear me. I'll have to look at my phone and get back into the phone call. I'm never looking at my phone while this happens so I don't know if I'm hitting something with my face while talking. I've tried turning the display off (with the top right button) while talking on the phone, but this doesn't seem to work. Anyone know what's going on with this?