I've got the 84106963798 (from 9/2005) BT/Assist TCU in my car. It was working fine with my Sony Ericsson T637. I just upgraded the phone to the new Sony Ericsson w800i. It pairs fine, the phone book transfers over no problem .... however whenever I make a call from the NAV screen (or the voice input system), the telephone audio always goes via the phone handset and not through the BMW BT/Assist system.

There is a option to manually force the audio to transfer to the BMW BT/Assist using the handset, once a call is in progress, however it doesn't seem to work - the phone seems to lock up if you try that !!

The odd thing is, if you make a call from the handset ... the audio fine and comes through the BMW BT/Assist system.

The phone is running s/w version: CXC1250316 R4CE012

Its very odd. I called up Sony Ericsson support and they said they would look into it, since my old T637 worked fine.

Anyone else tried the w800i with any of the BT/Assist TCUs yet .... ?

Cheers, Adrian