Hello, I have 5 lines at att that are eligible for upgrades. I opened 5 lines for my parents business so all their employees would have cell phones. Therefore, they would not need the upgrades. I also have a tmobile account that im currently using. I want to get a iphone and unlock it to use eith tmobile. My question is can I get an iphone and cancel the data plan after 30 days w/ no problems? I would be unlocking it and using it w/ my current tmobile account. Im just worried that att wont let them cancel the data plan. From what im gathering, it seems like att can only detect the iphone if you put in a att sim card right????? So they wouldnt be able to detect the iphone if i put my tmobile sim card in right????? Therefore, they wouldnt be able to add the data plan on my att account right???? So my plan is to upgrade one of the lines and pay the $30 data plan fee for the first month. Then, call and remove the data plan saying i either sold it or gave it to someone else....... Would that work? Also, if i cant bring the sim card for the line i am upgrading, will they still upgrade or do they need that sim to put in the new iphone? because that sim card is never going to go in the iphone. My tmobile sim card would be going in the iphone right after purchase. Would that be ok? Thanks in advance!