Thanks for the offer.. I may do that if I have no luck in France.
I have emailed Nokia to ask for the firmware history of the 6210 just for information (I'll post it here). It would be useful to know exactly from what version of firmware the 6210 starts to function with the system.
Emailed Nokia, Nokia who? I would be surprised if Nokia UK or Nokia France offered this detailed support. They didn't even know they had made a 6110 sometime before and reused the number (for the new 6110 that later on had to be extended with "navigator"). 6210 isn't a lot late product ;-)
Seriously, I actually managed to find SW bulletins for both the MB PSE (DME-1E) and the 6210 Nokia phone. DME-1E bulletins did not mention any phone SW releases but for the 6210 I did find some related notes.
SW version 4.36 introduces STP support (Smart Traffic Products), as used by e.g. Mercedes. Some ignitions status related fixes too.
5.17 has another STP fix, however I understand this one affecting data calls only after the phone has been used in the car.
5.27, 5.36, 5.44, 5.56 none for STP, as far as I could figure out.
My conclusion is that 4.36 should be usable and 5.17 and later OK. But since there are other bug fixes affecting normal phone use, the latest SW should be safe.