I wonder if any others have had this problem.

I'll be talking on the phone and suddenly a shrill feed back hits my speaker. I can mute, and the other side will mute, but it doesn't stop the feed back. I'll be forced to hang up

I cant find anything to adjust to stop this. Some times I will notice that the person on the other end was quite for a bit, make a noise like for example crumpling papers, then speak over this and the feed back hits.