If you're paying the $6 a month for the T-Zones then you won't be charged for data. If you're constantly accessing very very large amounts of data they might catch that you're running T-Zones off a device not meant to run T-Zones. I have 2 phones, a Berry with TMO and a Blackjack with AT&T (the only reason for that is so I can TEXT using QWERTY, don't hate!), but I'm running $10 unlimited Media Net on my Jack because the plan was set up with an LG flip phone. The data package should be $30, but it still works.