I activated my Lumia 900 on Friday but had to call to get my account provisioned to an LTE plan. The AT&T rep helped me out BUT either he made a misteke or intentionally put me on a 3GB tiered data plan. I'm a grand fathered unlimited data customer. I didn't pick up on this until Saturday when I logged into my account to see if everything went fine. I called AT&T immediately and they had to file a resolution that had to be approved to get my unlimited data back. He told me that they can't do that immediately on the phone. Today I got a message telling me that my issue was fixed and now I'm back on unlimited data with LTE.
Just keep in mind, if you're on an unlimited data plan they might without you knowing attempt to put you on a tiered data plan.
Just keep in mind, if you're on an unlimited data plan they might without you knowing attempt to put you on a tiered data plan.