I have an iPad Air 2 with Wi-Fi + cellular that I bought directly from Apple. I activated T-Mobile cellular data service on a month to month pre-paid data plan. I'm traveling to a location what T-Mobile service is bad so I wanted to switch carriers. My understanding of the Apple SIM in these iPads was that were not locked to a carrier after being activated and you could switch carriers at will unless you choose ATT who locks the sim to them. I can't figure out how to activate service on another provider with this SIM. I only can reactivate T-Mobile service. I thought T-Mobile was not locking the sim once used with them. Does anyone know if you can change from T-Mobile to another carrier without replacing the sim? I called T-Mobile and they were completely useless.