On the grandfathered unlimited data plan from verizon is it possible to easily add and remove the hotspot ($30) functionality from the phone? Say, If I go on a trip for 3 days only and want the hotspot functionality, through the phone/online, is it possible to add in the hotspot, and then remove it, just as I would if I were using the iPad 3? Or would I have to make a call to customer service?