I have a UDP, chatted with a rep online to confirm keeping my UDP if I upgraded. At first she said it would be gone. Then, when I questioned her about the $20 fee and now being able to use the DPP to keep unlimited data, she said that if it showed up as unlimited at checkup, I could keep it. To find out if it did, I had to click on VIEW DATA & TEXT FEATURES (it doesn't look like it is a clickable link but it is) under the existing lines at checkout. This showed that it was still there. Of course I took screenshots of everything, including the chat conversation, just to be on the safe side, but as of right now, everything still looks good. Also, when you are going through the checkout process, at the data plan tab, if you click on view new plan, instead of continue, it will try to move you out of unlimited data.