How to check if iPhone is unlocked (UK buyer checklist)

Buying a refurbished iPhone should feel like picking up a solid second-hand car from a trusted dealer, not like rolling the dice in a dark car park. Yet one small detail can turn a bargain into a headache: the phone being locked to a network provider.

If you’re searching for how to check if iPhone is unlocked, you’re in the right place. This UK buyer checklist for a used iPhone walks you through the quick checks you can do in minutes, what to ask before you hand over money, and what to do if the iPhone turns out to be locked to a UK network.

What “unlocked” really means in the UK (and why you should care)

An unlocked iPhone is free to use with any UK mobile network, so you can pop in an EE, O2, Vodafone, Three, giffgaff, SMARTY, Tesco Mobile, or VOXI SIM from a different network provider and it should just work.

A locked iPhone is tied to one network. It may accept the SIM physically, but the moment it tries to connect to cellular networks you’ll see messages like “SIM not supported” or “Invalid SIM”. It’s a bit like buying a kettle with a SIM card that only plugs into one socket in your house.

For refurbished buyers, unlocking matters for three big reasons:

First, price and choice. An unlocked handset is easier to resell and usually worth more. It also lets you move to a cheaper monthly deal without changing your phone.

Second, setup hassle. If you buy a locked model by mistake, you can end up spending days chasing the original network or the original account holder to request an unlock.

Third, risk signals. A seller who won’t confirm lock status, won’t share the IMEI, or dodges basic questions might not be hiding a locked device at all. They might be hiding something worse (like unpaid finance or a device that’s been reported lost).

Unlocked doesn’t mean “everything’s fine”, but it’s one of the easiest quality checks you can do early, before you get emotionally attached to that tidy-looking used iPhone 15 Pro.

The quickest checks on the iPhone itself (the ones to trust most)

If you have the phone in your hands, you can check lock status properly. Screenshots can be faked. A live check is harder to argue with.

Check “Carrier Lock” in Settings (fast, clean, reliable)

On iOS 14 or later, Apple shows carrier lock status directly:

1. Open Settings
2. Tap General
3. Tap About
4. Scroll until you see Carrier Lock (sometimes labelled Network Provider Lock)
5. If it says No SIM restrictions, the iPhone is unlocked

Apple confirms this exact route in its support guidance: Apple’s explanation of “No SIM restrictions”.

A practical tip: do this check after the phone has been restarted and connected to Wi-Fi. If the iPhone has only just been restored, it sometimes needs a moment to fully update carrier status.

Do the UK SIM swap test (the real-world proof)

Settings is strong, but the SIM swap test is the moment of truth. Borrow a SIM from a different UK network, even a cheap PAYG one from a corner shop. For eSIM users with digital-only plans, stick to the Settings check.

1. Turn the iPhone off
2. Eject SIM card from the SIM tray, then insert a SIM from a different network provider
3. Turn the iPhone on
4. Wait for signal, then try a call and mobile data

If it connects normally, it’s unlocked. If you get an error message, it’s likely locked.

This test matters because it checks what you actually care about: will it work on your network, on your commute, when you need it.

Quick reference: which method to use when

MethodBest whenWhat it tells youSettings “No SIM restrictions”You have the phone in-handLock status reported by iOSSIM swap testYou can borrow a second SIMWhether another network actually worksIMEI status checkBuying online, no phone access yetLikely original network and lock flag (varies by provider)

If Settings and SIM swap disagree, trust the SIM swap. It’s the “put the key in the door” test.

Checks to do before you buy (especially online or private sale)

When you’re buying a refurbished iPhone, you’re often working with limited info. A listing might say “unlocked” the same way a takeaway menu says “fresh”. It might be true, but you still want proof.

Ask for one specific photo

Request a photo of Settings → General → About showing “Carrier Lock: No SIM restrictions”. Ask them to include today’s date handwritten on paper in the same photo. It’s a simple honesty filter.

If the seller refuses, that’s useful information too.

Get the IMEI and do a sanity check

Ask for the IMEI number before you travel or pay. On the iPhone, it’s found under Settings → General → About, or by dialling *#06#.

An IMEI number helps you check basics and avoid wasting time. Use an online IMEI checker to verify the device status. If you’re meeting in person, ask the seller to enter the screen passcode as a basic check too. For an explanation of different ways buyers check lock status, Currys has a clear consumer guide: Currys guide to checking if a phone is unlocked.

One more angle: lock status isn’t the only trap. In the UK, you also want to be alert to iPhones that are blocked, blacklisted, or tied to someone else’s account. Lock status is just one light on the dashboard.

Watch out for the “it’s unlocked, trust me” script

Here are common lines that should make you slow down:

• “I’ve lost the box so can’t find the IMEI.”
• “It’s unlocked but I can’t show you because there’s no SIM.”
• “It was on the Vodafone carrier, so it’ll work on anything.”
• “Can you pay a deposit and I’ll post it?”

A genuine seller usually wants a smooth sale, so they’ll answer basic questions quickly.

If you want an extra viewpoint on what “locked” looks like in day-to-day use, Macworld breaks down the common symptoms buyers see: signs an iPhone is locked.

If the iPhone is locked, what can you do in the UK?

Finding out it’s locked doesn’t always mean you’ve been scammed. You might see a “SIM not supported” message when trying another SIM card. Plenty of iPhones start life on a contract, and some owners simply never bothered to unlock them.

But here’s the key: only the original network can unlock an iPhone. To get a legitimate unlock, contact your carrier. Apple can’t do it for you, and neither can a random shop promising instant magic.

Apple’s own guidance is blunt on this point: how carrier unlocking works.

Typical UK unlocking reality (what to expect)

• You’ll need the IMEI number. That’s non-negotiable.
• The original network provider may ask questions. They often want the original account details, or at least confirmation the device isn’t reported lost, stolen, or under active finance.
• Back up your iPhone before attempting to process an unlock. Timeframes vary. Some unlocks happen quickly, others take days.
• The unlock is usually remote. Once processed, restore your iPhone to allow the unlock to take effect when it connects to Wi-Fi or mobile data.

If you’re buying privately and the phone is locked, the cleanest fix is to have the seller request the unlock before you complete the purchase. If they won’t, walk away unless the discount is huge and you’re comfortable with the risk. Warn against using an unofficial unlocking service.

Don’t confuse “locked” with “Activation Lock”

Carrier lock is about mobile networks. Activation Lock is about Apple ID and Find My.

A phone can be carrier-unlocked and still useless if it’s signed into someone else’s Apple ID. Before paying, make sure the iPhone has been erased properly to factory settings and can reach the “Hello” setup screen without asking for the previous owner’s login.

Buying refurbished iPhones with less risk (and fewer surprises)

If private sales feel like guesswork, that’s because they often are. Buying a refurbished iPhone or used iPhone through retail is meant to remove the unknowns: testing, wiping, grading, and clear returns.

At Used Mobiles 4U, devices are checked for core functions, securely wiped, and prepared for clean setup (including processes to back up your iPhone and restore your iPhone), with network and SIM testing as part of the process. If you want the behind-the-scenes detail, see How UsedMobiles4U tests refurbished iPhones.

When you’re shopping, it also helps to buy from a retailer that clearly labels devices as SIM-free and unlocked, rather than burying it in vague wording. You can browse cheap refurbished iPhones in the UK and filter by the model you actually want, like the iPhone 14.

If you’re set on a newer handset, you can compare options like Refurbished iPhone 15 models or step up to Buy a refurbished iPhone 16 in the UK for longer iOS support and a fresher battery life profile.

A real-world example: one buyer picks up an iPhone from a marketplace listing, gets home, inserts their Three SIM, and the phone refuses it. They’ve saved £40 versus retail and lost three evenings to messages, missed calls, and awkward excuses. Buying refurbished from a retailer with returns can cost a little more, but it buys you time, clarity, and a way out if something doesn’t match the listing.

Conclusion: a simple routine that saves you money and stress

The safest approach to how to check if iPhone is unlocked is to use two checks that back each other up: the Settings “No SIM restrictions” line and a real SIM swap. Add an IMEI number check before you travel or pay, and you’ll dodge most of the classic traps.

If you want less uncertainty, buy from a UK refurbished retailer that tests devices properly and offers returns. You’ll spend more time enjoying the iPhone and less time trying to untangle its past.

FAQs

How do I check if my iPhone is unlocked without a SIM card?
Go to Settings, then General, then About, and look for Carrier Lock. If it says No SIM restrictions, it’s unlocked.

What does “No SIM restrictions” mean on an iPhone?
No SIM restrictions means there is no carrier lock or Network Provider Lock, so the iPhone isn’t tied to one network and should accept SIMs from any UK carrier.

Can an iPhone be unlocked but still not work with my SIM?
Yes. You could have a faulty SIM or eSIM, a network outage, or a phone issue (like baseband faults). Try a second SIM and test calls and data.

Is an IMEI check enough to confirm an iPhone is unlocked?
It helps, especially before buying online, but it’s not perfect. If you can, confirm using Settings and a SIM swap as well.

If my iPhone is locked, can I unlock it myself?
Not directly. The original network must process the unlock. Avoid services promising instant unlocks without the network’s involvement.

Do refurbished iPhones usually come unlocked in the UK?
Many do, but don’t assume. A good retailer will state it clearly and have checks in place before sale.

Author –

James Waterston (Owner, 25 years in the industry).