I had some experience with losing the unlimited data on my wife's number when she did a phone upgrade/new 2-yr contract. I was out of town on business when she had a phone problem and since she had been due for an upgrade she just did that to solve her problem. When I got back I found out that when she upgraded she lost her unlimited data when she upgraded. Since we were still in the 10 day return policy I took her new phone back and made them revert back to the old contract which included unlimited data. After talking to multiple VZW people, I learned that you will not lose your unlimited data if you currently have unlimited data and in the future you always "bring your own equipment". So I will now never do any more upgrades/2 yr contacts again. This kind of sucks because now I have to wait till the newer phones become reasonably priced on sites like swappa, but this does allow me and my wife to each keep our unlimited data since we will never be signing a new contract.