GeoSoul I did not want to disable Bluetooth completely, but my phone was picking up all calls on 5th ring any number that called.If you said what phone I could possibly be more specific, and I don't know the settings of an Iphone if that is your phone. However I do not believe the car radio will have that setting, it has to come from the phone.
For Android it may be in the Bluetooth setting of the phone either generic for all Bluetooth connections or within the specific Bluetooth connection.
Or very likely it will be in the call settings (on the phone) under accessories. That's where it is for my Samsung Galaxy phones.