During Apple’s recent iPad media event, the company was quick to glance over a feature that could have massive implications on the wireless industry. Those who purchase a cellular version of the iPad Air 2 or iPad mini 3 will receive what’s called the Apple SIM.
Essentially, it’s a universal SIM card that works with a variety of wireless carriers. It eliminates the hassle of having to switch SIM cards each time you want to use your device on a different network (while traveling or in areas where service is poor on a certain carrier but better on another, for example).
Instead, you simply select the cellular data account you want to use in the setting menu.
Apple lists AT&T, Sprint and T-Mobile as participating carriers in the US although early user reports suggest AT&T isn’t exactly playing by the rules.
Multiple users have noted that once you activate the Apple SIM on AT&T’s network, it can only be used on AT&T’s network and you’ll need a new Apple SIM if you want to change carriers in the future. Or in other words, AT&T is basically eliminating the entire point of the new SIM technology.
Apple has acknowledged this behavior in a new support document, highlighting the fact that AT&T dedicates Apple SIM to their network only and that you’ll need to buy a new Apple SIM if you want to use your iPad on another carrier.
When asked why they're locking the SIM card to their network, AT&T spokesperson Mark Siegel said it's just simply the way they've chosen to do it.
At this point, there’s no evidence that suggests other carriers are planning to do the same.
https://www.techspot.com/news/58573-att-lock-universal-apple-sim-if-you-activate.html
