iPhone and Microsoft sync issue

Hi Guys,

So, I synced my phone with my ford escape over bluetooth. Music works great, however I have one issue. When a call comes in my display shows incoming call but the phone button on the wheel does not answer the call. I have to answer on my iphone AND also have to select the source as SYNC for the call on the iphone.
My question is how can I get it to select SYNC as the source if avaliable for any incoming call ? If I dont select it my car display just says "in private"