My scenario is this: I have created a mount for my iPhone in my car which sits just above the head unit (pic attached). When the iPhone uses GSM (for calling or texting) I get unbearable interference in my sound system (painful high-pitched buzzing). If I move the iPhone a couple feet away, the interference goes away. I have helped the situation by placing a sheet of aluminum foil behind the iPhone, but it hasn't completely fixed the issue. Any ideas on how to solve this problem would be appreciated.