If you’ve searched “what does an unlocked phone mean” you’ve come to the right place.

An unlocked phone isn’t tied to a single network, so you can use any compatible SIM or eSIM. That helps when you switch provider, travel, or sell your phone. We’ll break it down, show you how to check your device, and point you to trusted refurbished options from The Big Phone Store, where all phones are unlocked.

Overview show

The short answer

Unlocked = no network lock. Works with any compatible UK network (EE, O2, Vodafone, Three) using a physical SIM or eSIM.
Since 17 December 2021, UK operators have been banned from selling new locked phones. You may still find older handsets that are locked — watch out for these.

Unlocked vs SIM-free vs Locked
Term	What it means	Typical source
Unlocked	Not restricted to one network; accepts any compatible SIM/eSIM	Refurbished sellers, some retailers
SIM-free	Sold outright without a contract; usually also unlocked	Direct from brands/retailers (e.g., Samsung UK)
Locked	Restricted to one network until unlocked	Older contract phones (pre-2021)

Tip: People use “SIM-free” and “unlocked” interchangeably. In the UK, SIM-free phones sold new today are typically unlocked, but always check the listing.

Why networks used to lock phones (and what changed)

Networks locked phones to keep you from switching mid-contract and to reduce support issues. Ofcom changed the rules to make switching easier, banning the sale of locked handsets from Dec 2021. If you’re buying used, a device from before that date might still be locked, so it’s worth checking.

How to check if your phone is unlocked

iPhone (iOS 14+)

Go to Settings → General → About.
Find Carrier Lock.
- “No SIM restrictions” = unlocked.
- Anything else = locked.

Android (steps vary slightly)

Insert a SIM from a different network and make a test call/data connection.
Or check your Network settings for available carriers and eSIM options.
Your retailer or refurbisher should also state lock status clearly in the listing.

Pros of buying unlocked

Easy switching: pick the best SIM-only deal without waiting for a contract to end.
Travel-friendly: pop in a local SIM or add a travel eSIM.
Resale value: easier to sell as buyers aren’t tied to a network.

Any downsides?

Up-front price: buying outright can cost more on day one compared to a subsidised contract.
5G/feature quirks: a few carrier-specific features (Wi-Fi Calling/VoWiFi branding) may need manual toggles or won’t appear with some MVNOs. Check your network’s support pages.

eSIM and unlocked phones

Unlocked applies to eSIM as well as physical SIMs. If the phone is unlocked and supports eSIM, you can add or switch plans digitally. Handy for short trips or temporary data plans.

Buying refurbished? What to check

Clearly stated “unlocked” in the product title or specs.
Network compatibility listed (UK 4G/5G bands).
Good return window and warranty for peace of mind (which you can get with us at The Big Phone Store with 30 day returns and 12 month warranty).
Battery health and grading explained in plain English.
For a deeper read, see our guides.

Commonly Asked Questions

Is SIM-free always unlocked?

In the UK, SIM-free sold new is typically unlocked, but always read the listing. Brand pages often describe SIM-free as giving you freedom to choose any network.

Can I unlock an older phone?

Yes. Networks can unlock eligible older devices (paid-off, not reported lost/stolen).

Will an unlocked phone work everywhere?

It must support the right bands and tech. In the UK, most mainstream phones do. If you import a device, check band support first. The Big Phone Store do not import, and only sell UK Certified devices.

Conclusion

“Unlocked” means you’re free to use any compatible SIM or eSIM. Since late 2021, new UK phones shouldn’t be sold locked, but it’s smart to verify status on used devices. Check settings, ask the seller, and buy from a refurbisher who states lock status clearly. The Big Phone Store exclusively sells unlocked, so you know what you’re getting.