Sorry, the OnStar is entirely based on a cellular service. So, don't expect it to be functional everywhere. The advantages over a simple cell phone are:
1. Larger, more powerful antenna.
2. Digital signal compression allowing to send data packets in short powerful bursts, which have much better chance to reach the nearest towers in decipherable, non distorted form.
3. Automated distress signal repeating.

So, if you have no OnStar in your car, you could consider investing in an antenna-buster for your cell-phone. I saw some good external antennas, which could outperform those used in the OnStar installation.

Or better yet, - invest in a PLB! cool

Edited by Alex (06/26/07 04:23 AM)