How do I integrate a Nokia Car-Kit with Audi A4 Concert II with Bose?

I have an '03 Audi A4 with the Bose upgrade. I am just about to get a handsfree phone car-kit fitted and have been told by the installer
that they cannot integrate the phone through the stereo speakers. I am unsure whether this is correct as in one of the menus of the Concert II there is a setting for which speaker the phone should come out of.
Can this integration be done? Does anyone know what connectors are on the back of the ConcertII? Are there any other connectors in to the system in the car? I have seen on some US postings that there is a 25pin D-plug somewhere in the car. Is this just for the USA?
Any help on this would be much appreciated.
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