I have a Pioneer AVIC-Z1 Navigation DVD in my car and the bluetooth with my new iPhone 4 does not allow the volume to be adjusted, like I could do with the 3G iPhone. So, the caller's voice is really loud and the echo is very bad. On the 3G I could use the volume buttons on the iPhone to turn down the caller's voice which made the echo mostly go away. Now, the volume buttons do nothing. Anyone having problems with their jawbone or other headsets? I was thinking I may have to switch to one of those instead...?