Can I use a T-Mobile SIM in an AT&T phone?

With long-term contracts on the decline, it's becoming easier to jump from carrier to carrier until you find the one you like the best. However, maybe you don't want a brand new phone every year or two. That's OK, but you need to make sure that your phone is unlocked (or whether it even possible, for that matter) and that it's compatible with the network you're moving to.

If you're leaving AT&T for T-Mobile, you need to get your ducks in a row before you pop in a SIM and wonder why nothing's working. Luckily, T-Mobile is probably the most accommodating when it comes to bringing your own phone, so you shouldn't have too much trouble.

Is your AT&T phone unlocked?

All devices purchased through AT&T will be locked to AT&T. There's a bit of a process to unlocking your phone, but it's easy and you don't have to wait on hold! You must first make sure you meet the eligibility requirements and then request an unlock code from AT&T.

Remember that AT&T can deny your unlock request if you're deemed ineligible. So, make sure your bills are paid up and you're in good standing and you haven't ticked off Wanda in accounts.

Is your AT&T phone compatible with the T-Mobile network?

To determine compatibility, you have to make sure that your unlocked AT&T phone supports the radio bands that T-Mobile's network uses. T-Mobile's main LTE bands are 2, 4 and 12, so you'll want to make sure your unlocked phone supports those specifically. Otherwise, you could be without LTE speeds and that's just no fun for anyone.

T-Mobile has a handy tool to help you out with the process. You just enter the type of phone you have and they'll let you know if it'll work.

The bottom line

So long as your phone is unlocked from AT&T and compatible with T-Mobile's network, it should work fine.

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