It's mainly for phones that don't have it, which are far and few these days, or phones who's signal is intermittent while traveling. The general idea is that it's supposed to be more of a constant signal for your current phone so that others traveling with you in the car can get the best signal. Also, for those without unlimited data, (also far and few) they don't have to use too much of their plan.I have never understood the need for a car wifi hotspot. I mean, the phone is right there plugged in to the car anyway. Why not use the hotspot that is on the phone that you are already paying for?