Phone problems GP3 Built 2011: Poor voice quality Which phone recommendation do you have?

Hello, during my Phaeton rides I often have phone calls to do. Unfortunately, the bad voice quality is often criticized. The participants describe mostly loud driving noises – even though it is really quiet in the car and poor connection quality, which makes calls partly impossible. The problem exists in all speed ranges, with various phones (iphone4, iphone 4s, Samsung Glaxy SII, SonyEricsson XPERIA and the Nokia X3-2, which rSAP In contrast, I always understand my callers extremely well.? Since I am dependent on good accessibility, this condition almost drives me into desperation. With my last vehicles this was never a topic. With my last MB I was able to make clear conversations at 250km/h. With my 2011-Phaeton this seems to be not possible at 100km/h. What experience have you made with the telephony in Phaeton? What telephone recommendations do you have? Greetings, Costa PS.: My workshop has already set itself the hands-free system and finds the quality normal.