I have a BMW Navigator V and tried 3 different bluetooth headsets now and about to buy a Sena 20S. I will be in the middle of a call and all of a sudden both parties start hearing their own voices only.

I have also tried 4 different phones and Garmin support is useless.

I found this post describing the exact same thing and wondered if others had the same issue http://support.sena.com/entries/49211570-I-hear-myself-talking