I'm onto my third iPhone 4 and will probably get a 4th one today. 1st - Got bricked updating to ver 4.1 exchanged it for another one. 2nd - Proximity sensor issue where the phone will randomly put people on hold, facetime or hang up on them when talking with it. Exchanged it for another one. 3rd - The one I got yesterday if you silghtly tap it on the back, the phone won't detect a network or sim card. I've tapped my coworker's iPhone 4 the same way on the back no issue... I also didn't have an issue with my previous 3 iPhones 4. I think I'm on a horrendous bad luck streak because I seemed to have encountered every known iPhone 4 problem that users have experienced. Apple awknowledges all these issues because they've offered to exchange my phone each time. I fear what would happen when my 1 year warranty expires. Keep in mind I received my first iPhone 4 at the end of August. I've been through 3 phones with 3 different problems over the course of 3 months. I am going back today again. I am sick of going to the Apple store.