Do you have to pay a monthly fee if you are using an uncontracted phone?

So I want to get an iphone 7+, but my family wants to switch providers from our plan in verizon to ting. (Ting is basically sprint it gets more complicated than that but that t the jist of it) But Ting doesn t have plans for like $30 a month or anything like that with iphones. I want to get an uncontracted iphone 7+ and use my old verizon sim card, until we switch to Ting. My dad says that if the phone isn t in a plan with verizon like im not consistently paying money for it every month then you have to pay $40 fee every month for the phone, while if you are in a contract and are paying regularly it is only $20. I don t think this is true, but he is persistent about it and I cannot find much on the internet about it and Verizon support wasn t much help. So if I am right and you have evidence of that could you put a link to the website you used so I could show him? Thank you very much i appreciate it.