iPhones come in two flavours, locked and unlocked, and it's important to be able to check which sort you've got. An unlocked phone can be used on any network, while a locked phone can only be used on the one it's locked to.

The iPhones you pay full price for (typically from the Apple Store) are unlocked by default. But an iPhone bought from a network, usually as part of an ongoing network plan, will be locked. This is normally for a set period, 18 or 24 months, and the cost of your contract covers part of the cost of the device.

It's not possible to tell, just by looking at the handset, whether an iPhone is locked or unlocked: Apple does not allow other phone companies to brand iPhones. (You don't get Three- or EE-branded iPhones, for example.) To confuse matters even further, some phones are locked when sold, but are unlocked at a later date when the original owner has paid off the initial contract.

But don't worry. It's relatively easy to find out if your iPhone is locked or unlocked, using either the Settings app or a SIM card, and in this article we're going to show you how.

How to check if an iPhone is unlocked in Settings

The simplest method of checking if an iPhone is locked or unlocked, and the one we'll use first, involves a quick look in the Settings app.

How to tell if an iPhone is locked or unlocked: Settings

You'll need to be able to power up the iPhone and access the cellular settings (you may need to enter the passcode). Follow these steps to check in iOS if an iPhone is unlocked:

  1. Open Settings.
  2. Tap Mobile Data > Mobile Data Options. (If the device is set to American English you'll need to tap Cellular > Cellular Data instead.)
  3. Check for an option named Mobile Data Network (or Cellular Data Network).

If you see an option for Mobile Data Network, as shown above, then your iPhone is most likely unlocked. This option should not appear on locked iPhones.

This method is not 100 per cent effective, however, and we get the impression that it has become less accurate since the launch of iOS 13. If you need to know for sure - if you're buying a second-hand iPhone, for example, and want to know if you're paying a fair price - you should use a SIM card to check that it is unlocked. We'll walk through that method next.

How to check if an iPhone is unlocked using a SIM card

For this method it's best to have two SIM cards, from different networks. Follow these steps to check that the iPhone is unlocked:

  1. Make a phone call using the current SIM card. Make sure it connects.
  2. Power off the iPhone. Hold down the Sleep/Wake button and use the Slide to Power Off option to switch off the iPhone.
  3. Use the SIM-card ejector tool (or a paper clip) to eject the SIM card from the iPhone.
  4. Insert your new SIM card.
  5. Press the Sleep/Wake button to wake up the iPhone.
  6. Make a phone call. Check that the iPhone can connect a call using the new SIM card.

If the phone call does not connect with the new SIM card, then the iPhone is locked.

How to tell if an iPhone is locked or unlocked: Slide to power off

You can sometimes get a carrier to unlock an iPhone by calling them, or use a third-party unlocking service such as Doctor SIM. For more on that, see How to unlock an iPhone.

Contact your carrier

It's not such a quick solution - it may take a while for the carrier to get back to you - but if you need to know for sure then it may be worth getting in touch with the network provider you've signed up to and seeing if they can help. Many carriers can check for you if you provide a handset's IMEI.

There are independent IMEI checking services too, but these services would always charge a fee for this (the legitimate ones would, at any rate). Your carrier may well offer the service for free. It can't hurt to ask, anyway.

Use an online IMEI checker

You know how to find your IMEI, right? Once you've got that code, you can go to one of the many IMEI-checking tools online and find out if the handset it's assigned to is locked or unlocked. The problem is that most of these services ask for a payment (although generally just a few quid).

There are free services too: you could try IMEI24.com, which appears legit and has been picked out by others. We must stress, however, that we don't know the company and cannot vouch for its services - other than to say that we've tried it, it returned a bunch of information that was correct (about age and type of device, when it was purchased, how long the warranty had to run and so on) and... it couldn't in the end tell us whether our iOS 13-based iPhone 11 Pro was locked or not. If you'd paid for the service that would be profoundly annoying.

How to check if an iPhone is locked or unlocked: IMEI checker