I have a 32gb iPhone 4 paired to both a plantronics voyager 510 and also an alpine head unit in my car. Moving even a foot away from the phone would cause my headset to fill with tons of static, and I wouldn't be able to hear the other person at all. Up until today I thought that the bluetooth interference problems I was having was due to a software problem, and I thought I was pretty much screwed until Apple released a new software update. I literally couldn't be more than a foot away from the phone without tons of static filling the earpiece. I decided to exchange my phone to see if it would help. The replacement is MUCH better at maintaining a bluetooth connection with both my earpiece, and also the alpine head unit in my car. Just posting it here to let people know that if they're having a problem with bluetooth interference, it's worth a shot to get your phone exchanged at the apple store.