Interesting, the cradle looks a lot like the Mercedes one for the 6310i / 6210. However the module in it isn't OEM. It's designed for original Nokia car kits. My brother in law has one of those modules in the Nokia car kit in his Saab. I was under the impression that the module wouldn't work in a manufacturers cradle only the Nokia one.
It is possible that the cradle is the Nokia one as opposed to a Mercedes one. Does your system work? Viseoo (who make that module) also make compatible adaptors for the Mercedes orginal kits.