I had a 2013 Silverado and I used the OnStar calling all the time, I actually had given up my cell phone and would just use the OnStar calling, I traded my 2013 for a 2017 Silverado, and I was not being able to get service where I lived, after couple calls to OnStar they said starting in 2015 they changed their service and had AT&T, and I knew that was the kiss of death because that was the cell service that I had and I knew there was no reception. So now I do not get service where I used to all the time with my 2013. You can imagine how frustrated I was after trading a 2013 for a 2017 that doesn't work as well. When I spoke with OnStar about the third time I finally was told that they had switched the way the service worked and they were aware that I was not getting coverage in some locations their technical people were looking into it and I was told if they were going to switch back they would give me an email that was about six months ago.