voice control button no longer working

Apologies from a newbie if this has been covered before - searched around without success:

I have just bought an A8 w12 MY05 - wonderful car but the MMI is erratic. The Voice control button was working for a short while but now no longer (after a few hours) - and the telephone (GSM with handset) states that "telephone is not installed" - I have put a sim in the handset unit without success and have reset the MMI using the three button method. However none of this makes any difference. The SW version is 0890 is this helps.

Any ideas?:confused:

I had a problem with my mmi system ... for me the car button kept getting stuck ... and this caused many issues ... so make sure all the buttons for the system go click, and none of them are getting stuck. I know it seems simple, but I overlooked it, and started worrying about a big repair bill!

I have found that the whole car and the bits in and on it are very sensitive to the cold, since its been so cold the last few weeks I keep losing steering wheel button function, automatic time via the satellite, boot opening and closing. Obviously made for the mifddle east customers and less so european ones...

Thanks - strangely it appears to work better (if that's the right term) when it is cold - once the car warms up it stops working - but having said that it also sometimes fails to work when it is cold.... could it be the button or the software?

If the temperature affects it, then its definitely hardware, the software doesn't know anything about temperature

Thanks. I have now done a software upgrade to 5570 and it appears to have solved the problem - stil no telephone but I have been informed that the module is most probably US so will have to replace that anyway.