My iphone 4 stopped thinking it was a phone last week. Went to genius bar & got a new phone under warranty--IT lost it's sound like my phone within a few hours. After trying all the tips--plug/unplug headphones, reset, RESTORED at least 50 times over the last 4 days I am again without sound. Must be a QC issue. I get the sound back on most restores, but poof it's gone again soon afterwards. ONLY works with bluetooth, not phone speakers or wired earbuds. I think I'm going back to genius bar to get another, but what is up????