What does this "We can hear the occupant over the speaker fine" mean? Does the radio get audio from the BT-receiverbox? Have you checked (with scope) if there is audio available all the time during the phone call i.e. is the other callers voice also there but the radio mutes it? Have you adjusted volume with wheel buttons during the call? If nothing else helps, it may be that the BT needs to be reprogrammed for the new audio configuration. I know that the DSP mutes after 40 seconds if it is programmed for non-navi system so maybe the BT does the same. The radio module is the same in all systems.