I just bought a used Chevy Impala 2005 and it has a microphone placed at the rear view mirror and its wire goes inside the hood. I don't know where it goes and I have no idea how to find its purpose. What should I do to figure it out?
GM vehicles often came standard with OnStar, GM's roadside assistance system. 2005 may be a little early for factory-installed Bluetooth.
Impala active noise cancellation began in 2014 model year, so it's OnStar or an aftermarket phone system (which need not be BlueTooth).