How can I keep my unlimited plan?

A

AC Question

I have an unlimited plan on a 4s with Verizon. My phone cracked so will it work if I give my son who currently has a 5c my available upgrade (he does not have one yet) and then he gets a 6 for himself and I take his phone? He does not have unlimited plan but I do so I am afraid if I use my upgrade it will kill my unlimited data plan.