Happy with your iPhone, but think you’re paying too much for data and texts? We’ve all been there, to be honest. Sometimes swapping mobile carriers is a good idea, but there might be a slight snag: If your iPhone is locked to a particular network, it’ll need to be unlocked before it will accept another carrier’s SIM card.

If this sounds complicated, don’t worry. We’ve reviewed all of the information you need to understand carrier unlocks below. Just keep in mind a carrier lock is different from a screen lock. The latter keeps you from accessing a phone while the carrier lock keeps you from using another network provider (if you have Verizon, you can’t use AT&T until the device is carrier unlocked).

How to tell if your iPhone is Locked

There are a couple of different ways to find out if your iPhone is unlocked. Let’s review the methods.

Not sure if your phone is locked? Well, this bit’s pretty easy. Just pop out your existing SIM and try a new one from another carrier.

If your iPhone is locked, you’ll get error messages such as “Invalid SIM” or “No SIM card installed.” This message might not mean that your phone is locked – it could just be a glitch in the iOS system. If you’re in this bracket, it’s just a simple case of flicking Airplane mode on and off and restarting the phone – or reseating the SIM card.

Alternatively, go to Settings | General | About and tap “Check for a carrier settings update.”

Note: It’s best to use a T-Mobile or AT&T SIM card if possible (on the GSM network). Some CDMA phones require very specific SIM cards that vary between phone models. This means that your phone may be unlocked, but it does not recognize the SIM card you’ve inserted.

Most carriers have the option to check if your phone is ready for activation on their network. AT&T, for example, has this website. You can input your phone’s IMEI number and receive an alert if it’s ready for activation or if it’s still locked into a previous carrier.

If you get the “SIM locked” message, you’re out of luck and will need to find a way to unlock your phone.

Find Out if a Phone is Unlocked Before Buying

One common issue with phones that aren’t unlocked is when they’re sold to another person. If you purchase a locked phone from the original buyer, you’ll be at their mercy to unlock it. Of course, you could check with your carrier to see if the IMEI is compatible, but this won’t always tell you if the phone is unlocked.

Your best bet is to meet the seller at your Carrier’s store and activate the service on the phone before paying for it (most honest sellers will do this). But, if you’re buying the phone on eBay or having it shipped to you, this isn’t an option.

Your next option is to use a third-party website to run the IMEI for you. But, as always, there are risks with this as well. Most of these sites charge a fee, and some aren’t even accurate. If you go to the original carrier’s website, you may have luck, but you’ll need the original account number and other key pieces of information the seller may not be willing to give you.

What Do I Need to Unlock my iPhone?

If you got your phone as part of a contract, your phone would be locked to their network only until the contract terms, lease, or installment are met.

If you bought your phone second-hand, it’s a little trickier: if you can’t get the seller to unlock it for you, you may need to jump through some hoops.

If the phone was originally purchased on a contract or lease agreement, you’ll need the original account holder’s information to have the phone unlocked. Otherwise, that phone will be stuck with that carrier forever.

How to Unlock Your iPhone

If your phone was purchased on a post-paid account on one of the top four carriers in the U.S., you need to go through that carrier to have the phone unlocked. Each carrier has its own process and criteria to release the phone.

How to unlock an iPhone 5, 6, 6s, and 7: Here’s How to Make a Locked iPhone Accept Any Sim

AT&T devices must be active on the network for a minimum of 60 days before the company will entertain unlocking it for you. AT&T’s unlock policy, assuming you meet the requirements, is one of the easier and more straightforward options.

AT&T makes it simple to have your phone unlocked. Visit their website for device unlocking and input your account/device information. You’ll receive a T&C email once you submit the request.

Check your email and follow the steps to confirm you’d like to unlock your device. Once done, you will receive an email that your device is unlocked within 24 to 72 hours.

Your iPhone will need to be free of any commitments or contractual obligations and will have had to be active on the T-Mobile network for at least 40 days to be eligible.

Visit your T-Mobile online account and access the phone you’d like to unlock under ‘View Account’ then ‘Lines and Devices.’ Submit the request to unlock that device and wait for the confirmation email.

Once the request is approved (about 48 hours), your phone is automatically unlocked for use on another carrier’s network.

Verizon has one of the most consumer-friendly unlocking policies because it will automatically unlock a device sixty days after purchase. If you have any trouble with this, you’ll have to contact the Verizon Customer Support Team to have your iPhone unlocked.

Aside from the iPhone 5 unlock confusion, the company has maintained a pretty straightforward policy on device unlocking. Based on the age of your iPhone, it’s most likely already unlocked.

Although Sprint is now T-Mobile, the unlocking policy for its older model iPhones is nearly unchanged. Sprint will automatically unlock a device once the conditions are met as long as they are SIM unlock capable. Unfortunately, devices manufactured before 2015 cannot be unlocked for domestic use (you can take it overseas after contacting customer support). The company will provide an MSL code for those devices, but iPhones do not use MSL (Master Subsidy Lock) codes, so it is pointless.

The company’s basis for this is that iPhones manufactured before 2015 were not required by law to be carrier unlocked, so the company never gave its customers the option. If you’re using an iPhone 6 or older, it isn’t likely that Sprint will ever unlock the iPhone.

If you need your device unlocked for international travel, or your device doesn’t unlock automatically, you can contact Sprint Customer Service.

Final Steps

Now that the carrier has (hopefully) unlocked your phone, put the new carrier’s SIM card into your phone. If you do not have a new SIM card yet (like you’re waiting to travel), back up your iPhone, reset it, then restore it with all of your data.

Doing a reset will ensure it is unlocked and ready for international travel. Before leaving, try to use another friend or family member’s SIM card (preferably AT&T or T-Mobile) in your phone to ensure it will work on the GSM network.

Frequently Asked Questions

Here are some more answers to help you better understand iPhone unlocking protocols and policies.

There are a lot of websites that promise to unlock your iPhone, especially the older models like the ones mentioned in this article. Unfortunately, it isn’t likely that any of these websites will have access to the information necessary to perform a successful unlock.

Most of these sites ask for payment information and device information to use in nefarious ways. It’s best to contact the carrier directly.

If you’re buying a phone from an individual or a third-party seller, you can look up the IMEI number on your carrier’s website. If it says it’s available for activation, you’re good to go.

The best option for anyone purchasing a new phone is to meet the seller at your carrier’s store. Doing this will ensure that the phone is activated and there’s no damage.

No. But, it is best to have an unlocked phone for international travel. The iPhone 5-7’s are a perfect travel phone. When you reach your destination, start a pre-paid service with a company in that country to avoid having to pay expensive international roaming fees.

Most carriers will put your phone number on what’s referred to as a “Military suspend.” This means that your monthly charges will be suspended during your employment, and your phone may be unlocked for international travel.

Check with your carrier before deployment to review your options.

Blacklisting is entirely different from carrier locks. When a device is blacklisted, that means it can’t be activated on any carrier. More often than not, this means that your phone was reported stolen.

If you did not initially purchase the phone, there isn’t much you can do to get the phone activated. Even calling the original carrier who blacklisted the device likely won’t help because it will appear to be someone else’s stolen property.

Contact the carrier you originally purchased the phone from if it’s blacklisted. Based on experience, this can be a lengthy process that needs to be escalated several times. The Blacklist is supposed to be a permanent block, so be prepared to put some time into it.

Some older model iPhones were not cross-carrier compatible. For example, the AT&T iPhone X was not compatible with the Verizon network. So, even if you have an unlocked iPhone, ensure that the carrier you want to activate it on is compatible with the model number you have.

The model number is listed on the back of your iPhone and looks something like a letter and a number combination (for example, ‘A1660’ indicates some iPhone 7 models).