I have an iphone 4 with verizon?

I have unlimited data. I'm looking to upgrade to the iphone 5 or 5s, but i don't want to lose my unlimited data is there anything i can do?

There's actually, I think. My mom uses less than 2GB a month, and we both have unlimited data, and I don;t want to lose it because I use like, 7 to 8 GB a month, and she was talking to some guy who worked at verizon, and he said since she uses less than 2, I can "give" my unlimited to her, and theyll just transfer it back to my plan. If you go to a verizon store and ask about this, I'm sure they'll do it.