I'm just curious, what does Onstar give for your phone that I don't get for free with My Link? My truck can see all my contacts and dial by voice commands and tell me when I'm getting a text. I'm curious as to why you pay Onstar for your phone and what features you get? Is it because of crossing the Canadian border?
The phone equipment installed by GM/Onstar in my truck operates at a higher power than my cell does. Typical portable cell phone operates at 0.6 watts, the installed Onstar phone operates closer to the maximum allowed 3.0 watts. The antenna for the Onstar phone is located on top of the roof, the antenna for the portable cell is inside the cab wherever I happen to have it laying/held at the moment.
For most urban environments, that won't matter as the 0.6 and portable antenna are at least, if not more than, adequate for the nearby cell tower. But that doesn't work so well when you're 20 miles away from the paved road and the next nearest house -- or sometimes when you're only 5 miles from those places.
More than once I've been able to call home from next to a trail in the woods when I couldn't get any signal on the pocket model. I've also sat in a campsite in the desert in Nevada and shared my Onstar phone for check-ins at home when no one in the group could get a signal from any portable when the carriers were Verizon, AT&T and Sprint.
For many, maybe even most people, that won't matter but for my uses, it does.
The better Canada/USA rates are gravy on top.
(In the interest of painting a full picture, this is belts and suspenders kind of logic as I usually travel with CB, HAM, portable cell, Onstar phone and a satellite rescue device -SPOT).