iPhone 5S and Ford Sync calls are not working correctly
I bought a 2013 Ford Focus with Ford Sync Touch. It was working fine with my iPhone 5 on iOS 7. I recently bought an iPhone 5S and everything seems to work fine until I make a phone call. The call connects but I cannot hear anything but loud crackling. I have the latest software updates on both the Ford Sync Gen2 3.6.2. and the latest iOS 7.0.4. I have reset both the Sync to factory settings and the iPhone to Factory settings. Still the exact same problem. Does anyone have any ideas on what the issue could be?
iPhone 5s, iOS 7.0.4