My iPhone 3G has been demonstrating a problem with streaming audio via Bluetooth. The problem is now fixed, though it required me to completely reset the device in order to get it to work.
I noticed that either using a Jabra Halo (stereo Bluetooth headset) or Sony MEX BT5700U Bluetooth-equipped head unit, the iPhone 3G would “stutter” (audio would go on for a moment, then off, then on again, etc.) whenever the iPhone went into “Auto-Lock” mode. Turning that mode off, the iPhone could work without any problem.
Tried everything I could think of to fix the problem; deleted Bluetooth profiles, reset the devices, even restored the iPhone (then recovered from a backup). Nothing fixed the problem.
Finally I called AppleCare yesterday. The last thing they had me try ended up working – I restored the iPhone using a fresh firmware image (again), but this time instead of recovering from a backup I “created a new phone.” That solved the problem.
Somehow, either an application setting or some other issue was causing Bluetooth audio to work weird.
Actually, I’ve had that problem and there is a less drastic step you can take. When it does that, click on the icon link to the sound devices at the bottom of your screen. Switch to Speaker so the sound is coming out of your speaker, and then switch back to the Bluetooth device. It’ll work for a while, but eventually it always seems to happen again and then you have to repeat that process.