We have this on our 2009 328i ...... dealer has not been helpful wanting to blame the phone but the iphone is on the recommended BMW list.
I think it has to do with the ambient noise level and the mike picking up background noise. The runflats were so loud on our car til we replaced recently .... phone sounds better now.
You are not trying to talk with the top down are you? In any event a vert might be noisier or maybe your runflats too?
"sometimes you're the windshield .... sometimes you're the bug"
2014 328i Mojave Metallic
2009 328i Black Sapphire Metallic
2007 328i Black Sapphire Metallic
2007 Honda S2000 Berlina Black
(Hey Jim... am I diversified?)