Until recently, if you wanted to unlock your phone in order to switch carriers, there was a good chance that you'd have to do it without the cooperation of the carrier you were with. You could search online for the codes that might unlock your device — or try to hack it in other ways. But what you usually couldn't do was call your carrier and ask how to do it.
As of February 11, 2015, that's all changed. Back in December of 2013, the major U.S. carriers set a voluntary deadline for a date by which consumers would be able to unlock their phones — provided they met certain criteria. (By the way, tablets can be unlocked as well, and the rules for unlocking are the same as for phones.)
So what are the new rules? Computerworld has put together everything you need to know about unlocking your phone, including how to find out if your phone is eligible for unlocking, how to unlock it with the major carriers, and how to move your phone from one carrier to another.
Check whether your phone is eligible for unlocking
Before getting started, you first need to know whether your phone is eligible to be unlocked. Yours might not be. If you bought your phone via a two-year contract from a mobile carrier, your phone is considered a "postpaid" device. You'll have to wait until your contract is up before you can unlock your phone. There's an exception, however — if you're willing to pay an early termination fee on your contract, you'll then be eligible.
If you bought your phone outright, it's considered a "prepaid" device and can be unlocked one year after its initial activation. There's one caveat, however: Your bill from your carrier has to be paid. So if you owe money, your carrier doesn't have to unlock your phone.
In either case, if your phone is eligible for unlocking, your carrier has to notify you. Typically, it will be shown on your bill.
Your phone needs to work with your new carrier
Presumably, you're unlocking your phone because you want to use it with a new carrier. Keep in mind that not all phones work on all networks, because some networks use different cellular technologies than others do.
U.S. cell phone networks use either CDMA (Code Division Multiple Access) or GSM (Global System for Mobiles) radio systems. Sprint and Verizon use CDMA, while AT&T and T-Mobile use GSM. Theoretically, a CDMA phone shouldn't work on a GSM network, and vice versa. But real life is more complicated than that. Phones that use the high-speed 4G LTE wireless standard should be able to work on any network, whether they are GSM or CDMA. However, not all 4G LTE phones work on all LTE bands, and so it's possible that a 4G LTE phone will not work on a specific network.
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