In the US Rover and Euro Rover that is not prewired for telephone there are two options for connecting the microphone wiring. The Bimmernav Bluetooth kit will ship using the direct wiring method where you can run the microphone wiring by tucking the wire into the roof headliner from the back to the front.

Euro Range Rovers that are prewired or equipped with the telephone system already simply require you to plug in the microphone into the overhead console without running any microphone wiring

Arrow below points to microphone wire connection