I'm currently grandfathered in on an unlimited data plan and have paid full price for an iPhone 5 to keep my plan. I will have an extra iPhone 4. Will Verizon allow me to add it to my current plan as a voice only device?
A data phone is a data phone. There used to be some work arounds...but now, as soon as you activate the iPhone's ESN on the account a data plan will be automatically added.