It appears to work independantly of a cell phone. I think it performs the same function as a typical cell phone hot spot. According to my research it comes with a 500MB allowance and then requires a sign up for a monthly data plan at extra cost.
A found this youtube video that gives more details.
The device acts like a normal wifi router. The difference is it provides internet connection using a mobile sim card similar to what happens when you use a cellphone for a hotspot. Do watch the cost for data. It could easily get very expensive if it isn’t unlimited data.
A better option could be to get a hotspot with your wireless carrier. For some, that means unlimited data and a discounted rate for the monthly charge.
Thanks guys thats kind of what I thought, my Silverado has a hot spot but I never used it. Mainly because I dont understand how it works, and I dont really need one. And I keep getting emails from these people and I was curious