On a side note here....
Those that have unlimited data usage should not allow their carrier to change you to the useless 2GB plan if you call to make some minor addition or change to your policy, like adding messaging or something. ATT tried to do that and I did not authorize them to make the change so I ended up with a huge bill from them one month and I called, made them change it back since I did not authorize it, and they removed the charges. Don't allow your carrier to switch you if you did not say it was okay. If they originally offered the Unlimited to you and that was your plan then they can't simply change it without asking you first. It is a breach of contract and you can go elsewhere without the early termination fee applying.
Agree. We are getting ready to add our daughter to our plan and thats going to be my first question. This will not affect my unlimited data usage correct? If it does, then we will find her some cheap text and phone service through another carrier.