I currently have three iPhone 5s's on my T-Mobile unlimited family plan. We all have unlimited data, never been throttled. Last month I had over 12gb usage just on my phone, and never had any data problems at all. If I went to the t-mobile store and added a new phone account to my account ($10 for add a line and $20 for unlimited data), and used that sim in my ipad air for LTE service, will t-mobile be able to figure out that I have that card in an ipad? I'm trying to get unlimited data on my ipad. I appreciate your feedback!!