I have a 2012 and added a mylink radio from a 2013. Got everything working well except when making calls over bluetooth. I can hear the other side fine but the microphone does not seem to work. I have tried different phones, different onstar modules (my original 2012 and the one from the 2013 mylink car). When I put the old radio back in the microphone works fine and using onstar (either module) works fine. Did the mylink unlock. Changed firmware from 24.1 to 24.5 and back. Seems to be something with the mylink headunit?