There are 2 telephone system types, every car I've come across with that cradle type has had BT fitted, as its a B7 then I suspect it has BT module fitted aswell, only way to tell is to scan with vcds for modules fitted which should show as 77 & in 77 it will show a part number, if that shows nothing, then check coding in instruments adaption channel for the bus to see if telephones enabled, of which it should be with the cradle fitted, the ultimate way to check is to check under the drivers carpet for the box to see if its in there.