Apple introduced a number of new features it hopes will change the game alongside the unveiling of its brand new iPhone 6 and iPhone 6 Plus, including a new reprogrammable SIM, Apple SIM. It might not be all it's cracked up to be, however.

T-Mobile CEO John Legere recently took to Twitter in what he described as a "Tweetstorm" to clear up some of the confusion surrounding what seems like a godsend for consumers who are sick of SIMs and carriers limiting their wireless mobility.

Before we dive into some of the specifics Legere points out, here's what Apple SIM is all about.

First things first. Apple SIM is only for the iPad Air 2 and iPad mini 3, the latest iPad models from Apple, only just recently announced. Apple SIM does not work, nor is it even a feature for the also-recently released iPhone 6 and iPhone 6 Plus. This is for tablets only.

Apple SIM was designed to allow the user to switch between carriers seamlessly. The SIM is essentially reprogrammable, meaning it should technically work on any network it is told to. This saves trips to the store and gives travelers greater freedom as they can utilize new networks in new countries around the world more easily. Apple plans on adding a numerous carriers to the list of Apple SIM-friendly networks around the world. Things aren't so simple, however.

To begin with, the largest network in the United States, Verizon, doesn't even support Apple SIM. The second-largest, AT&T, holds a similar stance: sure, it'll take Apple SIM, but once it's activated on AT&T's network, it becomes locked. There isn't anything the user can do except learn to switch out SIM cards.

"With us you can change carriers with this iPad any time you want," AT&T spokesperson Mark Siegel unconvincingly tried to convice Re/code that it's no big deal. "It is an unlocked device. ... All [you] have to do is switch out the SIM in the device so it works on another carrier."

As of now, only Sprint and T-Mobile offer pure Apple SIM compatibility, although as Legere points out in his tweetstorm, Sprint does come with some caveats.

Devices shipped to carriers are different than third-party or Apple retail versions. Verizon and Sprint iPad Air 2s and iPad mini 3s come with their own SIMs, while T-Mobile's and AT&T's models are equipped with Apple SIMs that are preconfigured to the carrier. In order to use a non-configured Apple SIM (the one you can truly "roam" between carriers with) as intended on Sprint's network, the consumer has to have their International Mobile Station Equipment Identity (IMEDI) registered with the carrier.

While the verdict is still out on exactly how well Apple SIM will fare among carriers who are usually too timid to allow the consumer much choice, the idea is solid -- it's just a matter or cutting through the archaic red tape of the U.S. wireless industry.  

As Legere put it, "Bottom line... it's complicated... and it is an emerging change in the mobile ecosystem that we will have to figure out as we go."

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