Car speaker/stereo help/cell phone buzz

Willow

We inherited a car and what the issue on this car is that I get the annoying cell phone buzz all the time. Any cheap easy fixes for this (I'm not looking for :turn off your cell or wrap in in tinfoil). It is an older car a 98. Our newer ones don't have this issue. It drives me crazy. Any way of shielding the oem speakers or what ever might need shielding?

Thanks