Purchased a T-Mobile iPad MiniR a couple weeks ago and put my AT&T SIM in it and it worked no problem. SIM was used in old iPad Mini non retina as part of a shared data plan FYI. Just a few days ago put the T-Mobile SIM in the older iPad Mini non retina that was purchased as an AT&T model and it worked fine and was able to activate the FREE 200MB data plan, no problems. All new iPad MiniR and Airs use same hardware for all Cellular models.