LG VX-9400

I've tried 3 different headsets with my 9400 and none worked satisfactorily. The last was a Plantronics 665 that sounded good in my office but when in the car (air off, windows shut) with the phone 3 feet away, there was so much static that the other party could barely hear me.

This makes me wonder if my phone is faulty or if the 9400 just doesn't work very well with bluetooth headsets.

What headsets are being used by folks and how well are they working? Is it likely my particular phone is at fault?

All comments appreciated!