You mean you have the factory-fitted cradle with operation via the steering
If so, the 6310i is the latest, AFAIK, that will work with that cradle and,
yes, it has been discontinued by Nokia. You should check with a telecomms
specialist at an MB dealer, but I think all later phones have different pin
arrangements and won't work.
I don't know if you can change the cradle to accept a newer phone -- ask MB.
I had a similar problem when I changed phones from the 5110 to the 6310i.
The cradle 'upgrade' charges were GBP 250 (in Germany) to GBP 400 (in
Britain). The price includes hardware and software changes. Fortunately I
was in a position to have my dealer offer to do it under warranty.
Merc had claimed that all Nokia 5000 and 6000 series phones worked in the
cradle originally supplied but the 6310i, which came out later, did not. I
think the 6250 (is that the right number?) did.
That's why the present Merc cradle system has become inappropriate and
Bluetooth connections have become important. I doubt you can retrofit
Bluetooth and achieve full funtionality via the steering wheel.
Anyway, check with your mobile phone provider. Mine (O2 in the UK) claims
to have stocks of 6310s. Otherwise look for second-hand, or an older model.
AFAIK the cradle should even work with a 5110 but I have not been able to
verify that personally.
Despite all the fancy new phones that sing & dance in colour, the 6310i is
hard to beat for making calls. Good, handy size, great Nokia menu and a
terrific battery life.
For direct contact replace nospam with schmetterling