We have had and used On Star for years. We were vacationing in the mountains around Durango, CO when our Son's wife became very ill about midnight. He carried her to our suburban and took off for the hospital soon there after he got lost on the dark mountain roads. He called On Star they located where they were and had EMTs dispatched to them.
After emergency surgery at the Durango hospital the surgeon told us that if she had arrived 45 minuets later she probably would not have survived. I had a stroke while driving to my grand daughter's house and became disoriented. My wife became concerned when I didn't arrive to pick the DGD up and called On Star who located the car's and my location and again dispatched EMTs to my great benefit. (Quick meds equaled good outcome) Both of our vehicles have On Star and and have current subscriptions. It is expensive but worth it in our opinion. The call range is not as good as it was with the previous analog service, but still has better than my handheld cell phone. (has better antenna). Last but not least if you have an accident with air bag deployment emergency services should be called unless it is violent enough to destroy the battery.
Drive safely,
ArizAl