I think that's just what happens. I called T-Mo before I pre-ordered a N900 to be absolutely sure what I was getting into. I was told my present Android data plan ($25 for unlimited data + 400 messages) would not work with the N900, but that all I had to do was call them back when I get it and they would do a quick re-configuration and all would be good. The change would take effect immediately with no change in the cost or service.