No no, it's not satellite service! It's cellular, and in many cases, analog at that.
If you don't subscribe, Onstar won't help you. At all. The dealer heard a story from a lady who was very upset. She let her Onstar subscription lapse, and then was upset when they wouldn't help her out with a stalled car . . . .
It sort of defeats the purpose of having a *subscription* if you can just use them anyway, eh?
Here's another on-star fact:
When you buy minutes on the phone, you only have a year from that time to use up all the minutes. Lets say you have 100 minutes left and the year is up. Guess what? you lose all those minutes you paid for. This happened to me and I called them to complain. I wish I was told that when I bought them or at least warned what was going to happen.
On-star admitted that they have had several complaints about that. They did give me back the minutes so I left it at that. I called just the other day and they still give you only a year from the puchase date of the minutes.