We have had this complainant and have experienced the same frustrations when we sent the phone out. We finally nailed it down when we noticed that squeezing the corner where the microphone was (where that little square dimple is) that the problem would go away. We started replacing the microphone with a similar one from Mouser (Made by PUI Audio) and never a complaint again.

This is specifically addressing the issue when you call a station and they are on hands free and all you hear is that aggravating noise and not the person. The problem with the speaker may be related, but I do not recall having that particular issue.