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What is an unlocked phone, and how do I know if my phone is unlocked?

Is your phone prisoner to a carrier?

Published onDecember 11, 2023

If you’re shopping for a new smartphone, chances are you’ll stumble across the term “unlocked phone.” What is an unlocked phone exactly, and how do you know if it’s unlocked? What’s more, do you even want an unlocked phone, and would it be safe to use? We answer all these burning questions inquiring minds want to know.


An unlocked phone is a device that has no carrier locks or restrictions. It's usually sold at full price. You can put any SIM card on it and use the handset with any carrier of your choice.


What is an unlocked phone?

OPPO Find X6 Pro alternative phones
Robert Triggs / Android Authority

What is an unlocked phone, anyhow? In simple terms, an unlocked phone is a device that has no ties to carriers. Typically, when your phone is on a contract, the associated telephone will remain locked to that network.

Why? Because wireless carriers sell phones at a discount. To recover financial losses from subsidizing, carriers lock customers into a multi-year contract of device payments while locking the phone to its network. You will pay for your plan every month, and the carrier will make its money back this way. Locking the device prevents customers from getting discounted phones and jumping networks without paying them off.

In addition to postpaid plans and phones, restrictions also apply to prepaid plans and associated devices purchased through wireless carriers. These phones do not have payment plans, but carriers still want time and financial investments before unlocking these devices.

If you want to dig deeper into the subject, we have a comparison between unlocked phones and carrier phones.

Can you put any SIM card into an unlocked phone?

You can’t install SIM cards from competing networks and expect instant connectivity. Even if the phone has the hardware to support other networks and you’ve made all the payments, it usually remains carrier-locked until you pay it off or meet specific requirements.

Unlock requirements for major USA carriers:

Of the three, Verizon is the only carrier that doesn’t lock phones even if contracts and payment plans aren’t complete. This stemmed from Verizon’s agreement with the Federal Communications Commission (FCC) when it acquired the block C spectrum. However, Verizon does lock your phone for the first 60 days after purchase. While it’s not perfect, 60 days is much shorter than the competition.

Unlocking versus rooting (or jailbreaking)

Phone with SuperSU root access stock 3
Edgar Cervantes / Android Authority

One of the big errors we see is the term “jailbreak” (or rooting) incorrectly associated with unlocking phones. Rooting pertains explicitly to software, as you remove the phone’s restrictions to install custom Android software or delete/hide bloatware apps. To that extent, you are “unlocking” the phone’s true potential or “unlocking” it from software-based restrictions. This is still not the same as SIM unlocking a device, though.

Typically, phone locking starts on the SIM card level to accept a specific mobile network code. But the other half of that restriction stems from your phone’s International Mobile Equipment Identity number (IMEI). This number is unique to each phone and used to identify all devices accessing terrestrial cellular networks, including smartwatches, laptops, modems, tablets, and more.

Moreover, all IMEI numbers have linked codes used to unlock a phone. Manufacturers store these codes in a database accessible by carriers and other third-party services. This prevents you from ripping the SIM card out of any device you’re currently buying through AT&T and using it on T-Mobile‘s network, for example. The IMEI number is still tied to AT&T; thus, the only way to unlock the phone is to make all the payments, send AT&T an unlock request, and get the unlock code.

According to a quick chat with T-Mobile, you can take this route or allow the carrier to pay up to $650 in device and termination fees. In turn, you must give T-Mobile the phone and purchase a new device through the company.

You can buy unlocked phones outright

Best Smartphones 4 End of Year 2021
Robert Triggs / Android Authority

You can get a carrier-free phone from most retailers, including Amazon, Best Buy, Target, Walmart, and more. You’ll pay the full price upfront versus the typical payment plan through carrier contracts; thus, the fancier the phone, the bigger the bite on your wallet.

For instance, you can get factory-unlocked versions of the Samsung Galaxy S23 series, the Sony Xperia 1 V, and Google’s Pixel 8 series. The list goes on.

Can you put any SIM card into an unlocked phone?

Before you purchase an unlocked phone, you need to see if it’s compatible. Main wireless networks in North America used two different standards: Global System for Mobile (GSM) communications, used by AT&T, T-Mobile, and a few prepaid carriers, and Code Division Multiple Access (CDMA), previously used by Verizon. However, Verizon has shut down its CDMA network as it’s moved to better, faster, 4G and 5G alternatives.

Now that all leading US carriers use GSM, it’s easier for unlocked phones to be compatible with any carrier, but there is another factor to look after. While AT&T, Verizon, and T-Mobile provide GSM-based cellular networks, they own and use different radio frequencies. T-Mobile openly provides its frequency list here, while AT&T has them here. Our friends at Swappa also have a nice list of Verizon’s bands. You’ll need to verify that the supported frequencies of the phone match the target carrier frequencies.


Google Fi Wireless logo on smartphone with SIM card and SIM ejector next to it Stock photo 7
Edgar Cervantes / Android Authority

Short for Subscriber Identification Module, the SIM card stores what your phone needs to access a specific network. This data includes your mobile subscriber identity number, encryption keys, contacts, SMS messages, etc. It’s a small, physical card that typically fits into a pull-out slot on the side of your phone. When you swap wireless carriers, you swap SIM cards as well.

Initially introduced in 1991, newer, smaller generations typically release every six to eight years. What we have today is the nano-SIM card from 2012, which is just over a square centimeter. Some devices also use the new embedded SIM module (eSIM) mounted inside the device, eliminating the need for swappable, disposable cards that can be lost or damaged.

Due to the difference between SIM cards and eSIM modules, check if the unlocked smartphone you want to buy includes the latter eSIM module, and if your wireless carrier supports it. Most carriers do these days. Additionally, the most recent and best phones support eSIM.

By the way, eSIM is likely the future. In fact, Apple has started removing physical SIM slots, and the iPhone 14 series only uses eSIM.

You’ll also find phones with two SIM card slots, allowing the device to access two separate networks. This is good for separating business and personal calls, as you’ll have two different phone numbers. This duality also provides better coverage, as you could switch from one network to another after moving into a dead area. You can use one SIM card locally and a separate one internationally, eliminating costly roaming fees.

How can I tell if my phone is unlocked?

Android settings app stock photo 1
Edgar Cervantes / Android Authority

If you’re currently making monthly device payments to a carrier other than Verizon, chances there is a lock on the device. Once you have paid off the device and submitted an unlock request, the first method of checking its status is to remove the current SIM card and install another card from a different network. A message will tell you if there’s a lock on the device.

Another way to find out if your device is unlocked is to use an IMEI checker. Swappa has a simple one. Here’s our guide to finding your IMEI number. When you have it, go to Swappa’s IMEI Checker, enter the IMEI, and Swappa will give you the results.

If you own an iPhone or cellular-capable iPad, you can check if your device is unlocked right from the settings. Convenient, right?

How to check if your iPhone is unlocked:

  1. Open Settings.
  2. Open General.
  3. Go into About.
  4. Scroll down to where it says Carrier Lock.
  5. If your phone is unlocked, this should say No SIM restrictions.

Again, if your qualified phone is locked to a specific carrier, you’ll need to send an unlock request. The required information may include the device IMEI number, your account number, the account owner’s social security number, phone number, and overseas deployment papers if needed.

The method of unlocking a phone using a code depends on the device. After requesting an unlock for an Android phone, customers receive a code from the carrier through a text message or an on-device pop-up window. The customer then shuts down the phone, removes the first carrier’s SIM card, installs the second carrier’s SIM card, powers on the device, and follows prompts to enter the unlock code.

Another route is to use a special app supplied by carriers. For example, Cricket Wireless provides the myCricket app with an “Unlock Device” option on the app’s sign-in screen. Once the app receives the required code, customers must reboot the phone to complete the unlock process. For iPhones and iPads, Apple provides unlock instructions here.

In addition to carriers, third-party services can unlock your phone, but doing so can violate your contract. For Android phones, you pay a flat fee in return for an unlock code. These third-party services have access to databases managed by phone manufacturers that contain unlock codes tied to the device IMEI. But be careful: some third-party services may not be legit and could run with your money.

Unlocked means freedom

google pixel fold on a phone call
Ryan Haines / Android Authority

Hopefully, you now better understand what “unlocked” means and how to tell if your current device is locked to a specific network. With an unlocked phone, you have the freedom to choose the best compatible wireless carrier. Even if you paid off the phone and completed contact obligations, the device is all yours, and you should be free to switch. Call your carrier today if you’ve met all the required obligations.


An unlocked phone is a device that has no network restrictions and can be used with any GSM network.

GSM stands for Global System for Mobile. It is a communications standard most networks across the globe use.

Verizon used to be the leading CDMA carrier in the USA. It has shut down its CDMA network, along with 2G and 3G. This makes it another GSM carrier now.

If you’re using an iPhone, you can see this information in the settings. Just go to Settings > General > About > Carrier Lock.

Android doesn’t have a similar feature. You’ll have to try putting a SIM card into the phone and see if it accepts it. You can also try an IMEI checker.

Most significant retailers have unlocked phones, and they will usually announce this somewhere on the buying page. You can try Best Buy, Amazon, Walmart, and Target.