You did a fine job of explaining the problem.
Speaking for myself I've never heard of your
setup so my suggestion is to call the manufacture
of the Car kit or the Base Unit.

In the USA bluetooth has been in use in BMW's
since 1999.

BMW X5 2000-2006 E53 BMW Bluetooth Kit for X5 1999-2006 E53 USA & (Euro 04/02-06)

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