link to a U.S. coverage map in pdf format
http://www.onstar.com/us_english/dow...age_map_us.pdf


Canada map
http://www.onstar.com/us_english/dow...ge_map_can.pdf


Quoted from
http://www.onstar.com/us_english/jsp...mp%3B+Hardware

Made shorter link
http://makeashorterlink.com/?R6CC12396

Q. How does OnStar work?
A. OnStar uses existing emergency service providers, cellular telephone
and satellite technologies. It operates alongside the electrical system
in your vehicle and is powered by your vehicle's battery. If your
vehicle's battery is damaged or disconnected, our service will not
function. Onstar currently uses the analog cellular network maintained
by separate cellular companies. This provides the broadest geographic
coverage of any current wireless system in the United States and Canada.