I have an unlimited 3g data plan with a Mifi2200. I have read a lot of posts today regarding how to change a grandfathered unlimited 3g data to 4g unlimited on a smartphone. So why is it not possible to do the same with a Mifi data plan? I have repeatedly been told that if I buy a 4g device, it would not work on my unlimited data plan. Why would it on a smartphone data plan?