If my iphone is connected to Wi-Fi, will facetime use the data plan?

It would be amazing if you answered!

No, in the top left corner of your screen if it says 3G or whatever, you're using the data you're paying for. If it says Wi-Fi and has the little Wi-Fi symbol, you're on Wi-Fi and you're not using your data plan no matter what you're doing that requires Wi-Fi. If you're not sure call Verizon or talk to a representative on the website. Hope i helped.