I have an iPad 1 3G 16gb that has a SIM card that has never been activated (when I click on account settings, it prompts for the credit card and which of the 2 plans and a new account and so on). I just bought another iPad 1 3G 64gb on Craigslist and it's SIM card has basically been deactivated by the previous owner (when clicking on the account, it prompts with the blanks for the user name and password). Are the SIMs tied to the devices? Or can I swap the non-activated SIM from the 16gb and put it into the 64gb and then go ahead and activate it on the 64gb? When I called AT&T, they wanted $15 to put a new SIM card into it. Thanks!