Like Apple has done with the iPhone 8/8 Plus, the iPhone X won’t have the same carrier compatibility for all variants. Whether you want to keep as many options open for switching to another carrier in the future, or would like to know which models will work for you if your first choice is out of stock as you go to preorder the device, follow along below…

While GSM is the standard for most carriers around the globe, Sprint and Verizon in the U.S. still use CDMA. While Apple hasn’t shared the iPhone X’s exact cellular specifications on its website, it does let us know that the AT&T and T-Mobile variants will be GSM only and won’t work with Verizon and Sprint.

While Apple is clearly detailing that all models are unlocked when choosing a carrier variant, the Verizon and Sprint models will have the most carrier flexibility, until we see Apple offer a SIM free version.

If the iPhone X cellular specs are the same as the 8, all models will feature the same 24 LTE bands, but the differentiator will be GSM/CDMA support.

Easy enough to remember, but here’s a quick chart to visualize it:

There are a couple ways this information can be helpful. First, if you’re planning on purchasing your iPhone X outright, you have the ability to choose from multiple models (unfortunately for now, Apple is only selling T-Mobile full price without needing to enter existing account details online).

The second option if you’d like to pay monthly, although a bit cumbersome would be if your first choice is sold out (or pushed back quite a ways)  to opt for a different carrier model with Apple’s iPhone Upgrade Program (as a new line). Then cancel the carrier plan that you had to sign up for to order the new iPhone and pop your SIM card in from your current carrier. Because they are all unlocked phones and there are no contracts, you can cancel the new plan that you don’t need and continue on as before, making monthly payments to Apple for your device. This again won’t work for online orders for now, but will if you try your luck in an Apple Store starting November 3.

There is one caveat to keep in mind that I’ve experienced, along with seeing others deal with: carriers sometimes have a bit more difficulty activating unlocked devices, particularly if the IMEI numbers haven’t been preloaded into their systems. It may take a call to your carrier’s customer support or a visit to your closest store to get going, but it shouldn’t be a prohibitive issue if you’ve got an iPhone model that’s compatible with your carrier.