Ok, since we are getting closer to do the OEM BT retrofit, I have to start a little side project as well.
Does someone know if you can connect two phone kits to the HU? I already have OnStar connected to the RNS-E (TEL+, TEL-, MUTE) but I don't have any device on address 77. This makes me to belive that I can safely connect the OEM BT interface to my CAN-bus but what does the HU say if there are two phone interfaces connected?
Did anybody in the US with OnStar or in Europe with the old style (non-CAN enabled) phone kit install a 3rd party BT phone kit in parallel?
If this is not possible, what's required to disable OnStar/Audi Telematics completely?