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HolidayBuyer's Guide
Phones

How to unlock your phone for use with another carrier

Learn how to check if your phone is unlocked and, if it isn't, how you go about making an unlock request with AT&T, Sprint, T-Mobile and Verizon.

CNET

Happy with your current phone but not your current network? Thanks to the Unlocking Consumer Choice and Wireless Competition Act, it's perfectly legal to unlock your phone and switch to a new carrier.

Unlocking your phone is legal, but some restrictions, as they say, may apply. Your phone needs to be fully paid for, whether you have a completed installment plan or come to the end of a two-year contract. If you have a prepaid phone, carriers can't lock you in for more than 12 months.

In addition, the phone you seek to unlock must not be reported lost or stolen and your account must be in good standing.

We'll cover how the big four carriers in the U.S. -- AT&T, Sprint, T-Mobile and Verizon -- handle unlock requests. Before we get to the carriers, however, you should check to see if your phone is locked.

Find out if your phone is already unlocked

You may not need to request your carrier to unlock your phone. Verizon, for example, largely sells unlocked phones.

The sure-fire way to check to see if your phone is unlocked is to call your current carrier and ask. If you aren't up to the task of navigating customer service and you have a GSM phone (uses a SIM card), you could swap in a SIM card from another carrier to see if it works. If you can make a call or send a text with the new SIM card, then your phone is unlocked.

Now, let's have a look at the carriers.

Verizon

Verizon states on its Device Unlocking Policy page, "We do not lock our 4G LTE devices, and no code is needed to program them for use with another carrier. We do not lock our 3G devices, other than our non-iPhone 3G World Devices."

In other words: If you have a recent iPhone with 4G LTE service, you will not need to unlock your phone. If you have a locked 3G World Device phone with Verizon, you can use unlock code 000000 or 123456 or call 800-922-0204 for help.

Verizon's 3G Prepaid Phone-in-the-Box phones can be unlocked after 12 months of service.

AT&T

With AT&T, you can avoid calling customer service and use its Device Unlock Portal to unlock your phone.

Although the law states that a carrier can't lock prepaid phone customers more more than 12 months, AT&T cuts that service time in half. For prepaid or GoPhone accounts with AT&T, you can unlock your phone after six months of service.

T-Mobile

T-Mobile will unlock your phone but restricts you to two unlock codes per line of service per 12 months.

For prepaid plans, you can unlock your phone after 12 months of service. You can also unlock it if it's had more than $25 in refills for basic phones or $100 in refills for smartphones.

If you have an Android phone, you can use T-Mobile's Device Unlock app to request T-Mobile unlock your phone. Others will need to contact customer support at 877-746-0909.

You can read the details of T-Mobile's policy here.

Sprint

Sprint automatically unlocks recent phones. Sprint will automatically unlock any phone released after February 2015 once the installment plan is completed or the device is otherwise paid off. Sprint adds one restriction in addition to the usual bits about your account being in good standing and your phone not being reported as lost or stolen: Even if you paid in full for your phone up front, it needs to be active Sprint's network for at least 50 days before you can unlock it.

For older phones, Sprint will send you an unlock code when you have paid in full for your phone. It will notify you when you are eligible for the unlock code. You will need to contact Sprint customer service at 888-226-7212 to get the unlock code.

You can read the fine print for Sprint's unlocking policy here.

Closing caveat

For older (read: non-LTE) phones, you must take in account that Sprint and Verizon are on the CDMA network, and AT&T and T-Mobile use GSM. These two 3G networks are not compatible with one another. To muddy the picture further, Verizon 3G phones aren't compatible with Sprint 3G and vice versa even though they both use CDMA. Generally speaking, however, swapping a SIM card from one unlocked GSM 3G phone to another will be met with success (AT&T to T-Mobile or vice versa).

Switching a 4G LTE phone to another carrier is less complicated because all the carriers got on the same page with LTE for their 4G coverage.

In the end, it's a good idea to check with your intended new carrier if your phone is compatible before attempting to switch.

For more, I'll turn it over to CNET's Marguerite Reardon on the ins and outs of switching carriers.