An unlocked phone works with a SIM card from any network. A SIM-free phone is one sold without a contract or SIM card attached. In the UK the two terms now overlap almost completely, because Ofcom banned mobile companies from selling locked handsets from 17 December 2021. This guide explains what each term means, how to check a phone yourself, how eSIM and 5G fit in, and how to work out whether an unlocked refurbished phone plus a SIM-only plan costs you less than a contract.
What does "unlocked" mean on a UK phone?
An unlocked phone has no network restriction, so it accepts a SIM or eSIM from any UK provider: EE, O2, Vodafone, Three, or a smaller provider that runs on one of their networks. A locked phone only works with the network that locked it. To use any other network, the provider that locked it has to remove the lock.
The lock is a software restriction tied to the handset. It has nothing to do with the screen lock, Face ID or your PIN. It also has nothing to do with Activation Lock on an iPhone, which links the phone to the previous owner's Apple Account. Refurbished buyers sometimes confuse these. Here is the difference:
- Network lock (also called a carrier lock or SIM lock): limits which network's SIM the phone accepts.
- Activation Lock / account lock: stops a stranger setting up the phone until the previous owner's account is removed.
- Screen lock: your own passcode, fingerprint or face unlock.
When you buy a used phone you need the first two cleared. At The Tech Gadgets, every refurbished phone is unlocked for all UK networks. Each one is also signed out of the previous owner's account before dispatch, and on iPhones that means Activation Lock is switched off.
What does "SIM-free" mean?
A SIM-free phone is sold on its own, with no airtime contract and usually no SIM card in the box. You pay for the handset once, then choose any SIM or plan you like. "SIM-free" describes how the phone is sold. "Unlocked" describes what the phone can do. Most SIM-free phones sold in the UK today are also unlocked, but the two words do not mean the same thing.
Retailers use "SIM-free" and "unlocked" almost interchangeably. When you read a listing, the word to look for is unlocked. A SIM-free phone that is still network-locked, such as an older contract handset, won't take another network's SIM.
Unlocked vs SIM-free: what's the difference?
Unlocked is about network compatibility: the phone accepts any network's SIM. SIM-free is about how it's sold: no contract and no SIM bundled. A phone can be SIM-free and still locked, for example a pre-2021 contract handset resold second-hand. A phone can also be unlocked but come with a SIM. The safest listing says both.
| Term | What it describes | What it guarantees | What it doesn't guarantee |
|---|---|---|---|
| Unlocked | The handset's network status | Works with any UK network's SIM or eSIM (subject to the phone supporting that network's bands and features) | That it comes without a contract |
| SIM-free | How the phone is sold | No airtime contract, no monthly bill attached | That it's unlocked |
| Unlocked + SIM-free | Both | You own the phone outright and can use any network | Software support length, battery condition, grade (check these separately) |
Can UK networks still sell locked phones?
No. Under Ofcom rules in force from 17 December 2021, mobile phone companies in the UK are banned from selling customers locked handsets. Ofcom said its research found locking put people off switching provider, and that unlocking could be complicated and cost around £10. Phones bought before that date, or bought abroad, can still be locked.
That matters for second-hand buyers. A phone sold on a UK contract in 2020 could still be locked today, as could an imported phone. For older stock, check the phone itself, or buy from a seller who states it's unlocked and accepts returns if it isn't.
Ofcom's announcement of the ban also pointed to its text-to-switch process. You can keep your number and move networks without phoning your old provider to negotiate. An unlocked phone makes that switch painless, because you only swap the SIM.
How do I check if a phone is unlocked?
On an iPhone, open Settings, tap General, then About, and look at Network Provider Lock. "No SIM restrictions" means the iPhone is unlocked. Android phones have no single universal setting, so the reliable test is to insert a SIM from a different network and see whether the phone connects, makes a call and uses mobile data.
iPhone: Settings > General > About
- Open the Settings app.
- Tap General.
- Tap About.
- Find Network Provider Lock (US-English software calls it "Carrier Lock"). If it says No SIM restrictions, the iPhone is unlocked.
Apple's UK support page is clear that Apple itself can't unlock an iPhone for use on a different network. Only the network provider that locked it can. If you're buying a used iPhone in person, ask the seller to show you this screen before you pay. When you buy a refurbished iPhone online, check it on the day it arrives.
Samsung, Google Pixel, OnePlus and Nothing: the SIM test
The dependable check on any Android phone is practical:
- Borrow a SIM from a different network to the one the phone was first sold on. If you don't know which network that was, any SIM will do.
- Power the phone off, insert the SIM, and power it on.
- Look for signal bars and the network name. A locked phone typically shows a message asking for an unlock code or saying the SIM isn't supported.
- Make a call and load a web page on mobile data (Wi-Fi off) to confirm voice and data both work.
If you have an eSIM-only plan, the equivalent test is adding the eSIM and confirming it activates and connects.
What if the phone turns out to be locked?
Contact the network that locked it. For a phone you bought from a retailer as "unlocked", report it straight away. At The Tech Gadgets, faults, wrong items and damage must be reported within 3 days of delivery, inside a 30-day returns window. See our refund policy for the details.
eSIM vs physical SIM: does it matter on an unlocked phone?
An eSIM is a digital SIM built into the phone, which you download from your network instead of inserting a card. Unlocked phones can use either, provided the model supports eSIM and your network offers it. Apple says iPhone XS, XS Max, XR and later support eSIM. Google says Pixel 4 and later phones work with eSIM.
Here's how support looks across the brands you'll find in refurbished stock:
- iPhone: eSIM on iPhone XS, XS Max, XR and later. Apple's eSIM page says you can store eight or more eSIMs. Some iPhone models are eSIM-only in certain countries, so if you need a physical SIM tray, confirm the exact model before you buy.
- Samsung Galaxy: Samsung UK lists eSIM support on the Galaxy S20, S21, S22, S23, S24, S25 and S26 families and on the S23 FE, S24 FE, S25 FE and S26 FE. Samsung adds a caveat: depending on the country of origin, eSIM may not be supported even on a listed model. eSIM on Galaxy A models is limited to selected models and regions.
- Google Pixel: Pixel 4 and later support eSIM, and Pixel 7, Pixel 7 Pro and later can run two eSIM profiles at once.
- OnePlus and Nothing: eSIM support varies by model and region, so check the specific model's specification page.
Samsung UK lists EE, H3G, O2, Sky, Spusu UK, Three, Truphone and Vodafone as UK carriers supporting eSIM on Galaxy phones. Smaller providers vary, so check with yours before switching from a physical SIM.
One practical tip for refurbished buyers: an eSIM belongs to your network account, not the handset. If you're moving from an old phone, use your network's or the phone's eSIM transfer process. Don't factory reset the old phone until the new one is connected.
Will an unlocked phone work on 5G in the UK?
Only if the phone itself has 5G hardware, your network supports 5G where you are, and your plan includes 5G. Unlocking doesn't add 5G. Apple says iPhone 12 models and later work with 5G networks. On Android, 5G depends on the exact model and variant, which is why listings often put "5G" in the name.
In practice:
- iPhone: iPhone 12 and later are 5G-capable. iPhone X, XS, XR and the iPhone 11 family are 4G only. That's fine on UK 4G networks, but you won't see the 5G icon.
- Samsung: check the model name. In our range, for example, there's a Galaxy A16 5G and a separate Galaxy A16 4G.
- Plan matters too: Apple's own troubleshooting advice is that if 5G doesn't appear, you should check with your network that it supports 5G and that your plan includes it.
What about very old phones and the 3G switch-off?
Ofcom confirms that Vodafone, EE, Three and O2 have all switched off their 3G networks. A phone that can only use 2G or 3G for data won't get most mobile data any more. On Three, which has no 2G network, such a phone can't even make calls. This matters most if you're comparing very old, very cheap handsets: check that any phone you buy supports 4G at a minimum.
Which UK networks will an unlocked phone work on?
An unlocked UK-spec phone works on the four UK network brands (EE, O2, Vodafone and Three) and on providers that use their networks, such as giffgaff, which runs on O2's mobile network. The phone must support the network's bands and features. A UK-model phone from a mainstream brand normally does.
Providers without their own masts are called MVNOs (mobile virtual network operators). Your coverage depends on the host network, not the brand on the SIM. giffgaff's own help page confirms that a giffgaff SIM works in an unlocked phone, and that phones locked to O2 also work because giffgaff uses O2's network. A phone locked to any other network has to be unlocked first.
That's the hidden benefit of buying unlocked: you can pick the cheapest SIM-only plan with good local coverage and switch whenever a better deal appears.
Why can an unlocked refurbished phone plus SIM-only cost less?
A phone contract bundles two things into one monthly bill: the handset and your airtime. Buying an unlocked refurbished phone outright separates them. You pay a lower one-off price for the phone, then pay for a SIM-only plan. Whether you save depends on real prices, so compare total cost over the same period rather than monthly bills.
A worked method (hypothetical numbers)
The figures below are made-up examples to show the calculation. They are not quotes from any network or from us. Plug in the real prices you're offered.
| Step | Contract route | Unlocked refurbished + SIM-only route |
|---|---|---|
| 1. Upfront cost | Upfront fee, e.g. hypothetical £30 | Phone price: see today's price on the product page |
| 2. Monthly cost | Contract monthly, e.g. hypothetical £40 | SIM-only monthly, e.g. hypothetical £12 |
| 3. Period | 24 months | 24 months |
| 4. Total = upfront + (monthly × months) | £30 + (£40 × 24) = £990 (hypothetical) | Phone price + (£12 × 24) = phone price + £288 (hypothetical) |
Add the real price of the phone you want to see the difference over two years; it could favour either route. Contracts sometimes include perks, and a cheap phone can come with a short software-support window. Three adjustments make the comparison fairer:
- Match the data allowance. Compare a SIM-only plan with the same data, roaming and features as the contract.
- Include price rises. Read each contract's terms for annual price changes and add them to the monthly figure.
- Factor in resale or life left. At the end of a contract you own the phone (on most handset contracts). With the outright route you own it from day one. A model with years of software updates left is worth more to you than one near its end.
Our guide to the cost of owning a refurbished flagship covers warranty, repairs and care plans, the other costs worth adding to the outright route.
Cheap refurbished iPhones, unlocked: where to start
If you want a cheap unlocked refurbished iPhone with 5G, the iPhone 12 and iPhone 13 are the usual starting points in our range. Both are 5G-capable (Apple: iPhone 12 and later) and both support eSIM (Apple: iPhone XS, XR and later).
- Refurbished iPhone 12: see today's price on the product page.
- Refurbished iPhone 13: see today's price on the product page.
Shop refurbished iPhone 13 (unlocked) →
For a tighter budget, see refurbished iPhones under £200. For a model-by-model shortlist, read the best refurbished iPhone to buy in 2026.
Samsung SIM-free phones in the UK: what to look for
For a SIM-free Samsung, prioritise software support over raw specs. Samsung's security-update scope page currently lists the Galaxy S23, S24 and S25 families for monthly security updates. The S22 family and S21 FE are on quarterly updates. Older S21, S20 and S10 models no longer appear on either list.
- Refurbished Galaxy S23: see today's price on the product page.
- Refurbished Galaxy S24: see today's price on the product page.
- Refurbished Galaxy A56 5G: see today's price on the product page.
Browse all refurbished Samsung phones, or read the best refurbished Samsung phones for 2026.
What you get with an unlocked refurbished phone from The Tech Gadgets
- Unlocked for all UK networks and signed out of the previous owner's account (Activation Lock off on iPhones).
- Tested, cleaned and factory reset. Devices are activated before dispatch for testing.
- Battery health of at least 85% measured at dispatch on Like New, Excellent and Very Good grades.
- 12-month warranty covering manufacturing defects and functional malfunctions. It excludes physical, water and electrical damage, and battery defects or reduced capacity. Full terms are on our warranty policy page.
- 30-day returns, plus your 14-day legal right to cancel an online order.
- Same-day dispatch on orders placed by 3pm Monday to Friday, from Manchester. Free UK delivery over £50 (see our shipping policy).
Our phones are refurbished by The Tech Gadgets, not by Apple or Samsung. The grade tells you the cosmetic condition. Our condition grades explained walks through Like New, Excellent, Very Good and Fair.
Shop all unlocked refurbished phones →
Frequently asked questions
Is an unlocked phone the same as a SIM-free phone?
Not exactly. Unlocked means the phone accepts any network's SIM. SIM-free means it's sold without a contract or SIM. Most SIM-free phones sold new in the UK since December 2021 are also unlocked, because Ofcom banned the sale of locked handsets. Older second-hand phones can still be SIM-free but locked.
Are all phones in the UK unlocked now?
Phones sold new by UK mobile companies since 17 December 2021 should be unlocked, under Ofcom's rules. Phones sold before that date, or imported from abroad, may still be locked. Check any used phone yourself or buy from a seller who states it's unlocked.
How do I know if my iPhone is unlocked?
Go to Settings, then General, then About. If "No SIM restrictions" appears next to Network Provider Lock, the iPhone is unlocked. If it doesn't, only the network that locked it can remove the lock. Apple can't do it.
Will a giffgaff SIM work in an unlocked phone?
Yes. giffgaff says its SIM works in any unlocked phone, and also in phones locked to O2, because giffgaff runs on O2's mobile network. A phone locked to another network has to be unlocked first.
Can I use an eSIM on a refurbished phone?
Yes, if the model supports eSIM and your network offers it. Apple supports eSIM on iPhone XS, XS Max, XR and later. Google supports it on Pixel 4 and later. Samsung UK lists the Galaxy S20 to S26 families and recent FE models, with a caveat about country of origin.
Does unlocking a phone give it 5G?
No. 5G depends on the phone's hardware, your network's coverage and your plan. Apple says iPhone 12 and later support 5G. On Android, check that the exact model and variant is 5G-capable before you buy.
Is it cheaper to buy an unlocked refurbished phone and go SIM-only?
It often can be, but it depends on real prices. Add the phone's price to the SIM-only monthly cost over 24 months. Compare that with the contract's upfront fee plus its monthly cost over the same period, including any annual price rises. Use the worked method above with the prices you're actually offered.