anonymous wifi hotspot

trac phone and some other providers offer prepaids with 4G data plans and android OS. anyone know anything about these? when you buy one, can you use a visa gift card to register and pay for it so it's anonymous? I'm looking for a way to get a portable wifi hotspot with a dynamic IP. I can do it with my own phone and a variety of apps that make it a hotspot, but that's on my plan with my name, etc. Not trying to do anything illegal per se, I just prefer anonymity. Any input is appreciated.

yea you can do that with prepaids but never seen android on trac but i could be wrong, try virgin mobile