IPhone 4 doesn't allow reasonable range and other issues with bluetooth headset. Fyi, tried with Apple Bluetooth headset which worked perfectly with IPhone 3G & IPhone 3G-S. Issue, you can have IPhone 4 in shirt or pant pocket and bluetooth will disconnect. Also, you can have IPhone 4 inside car and close the door while standing right outside the door and bluetooth disconnects. This never happened with previous models including IPhone 3G-S with IOS 4 installed.
Other bluetooth issues: as others reported - muffled sound quality to person your talking to. Time delays and disconnects with bluetooth Uconnect. IPhone 4 won't let you change between your car audio phone feature back to IPhone 4 without freezing.
The original s/n looks like it was week 25. But, I am not sure if some component started aging prematurely on the previous phone and affecting the BT radio.
As has been pointed out in this and other threads. The garbled BT audio issue is resolved in iOS 4.1 beta 3. The full production version is likely just around the corner. Hang tight.
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IPhone 4 Bluetooth Issues
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