How to Check If a Phone Is Unlocked Before You Buy It (iPhone & Android)

"It’s unlocked, I promise" is the most expensive sentence in the used-phone market. An unlocked phone works on any compatible network; a locked one is worth far less and may not work for you at all. Here is how to verify unlock status yourself — on iPhone and Android — before your money changes hands.

iPhone: check Carrier Lock in Settings

Open Settings → General → About and scroll to Carrier Lock. If it says No SIM restrictions, the iPhone is unlocked. If it names a carrier, it’s locked to that network until unlocked. Newer iOS may label this Network Provider Lock — same meaning.

Android: the SIM swap test

The most reliable check is physical: insert a SIM from a carrier different from the one the phone was sold on. If you get signal and can place a call, it’s unlocked. If you see "Invalid SIM" or "SIM not supported," it’s locked. Some Android brands also show lock status under Settings → About or a carrier’s BYOD IMEI checker.

The SIM test beats any screenshot

Sellers can fake a settings screenshot in minutes. The SIM swap is the one check that can’t be faked — either the phone connects to your network or it doesn’t. If you’re buying in person, ask the seller to let you insert your own SIM before you pay.

Also check blacklist and iCloud

Unlocked doesn’t mean clean. A phone can be unlocked but blacklisted (reported lost or stolen) or still Activation-locked to a previous owner. See our carrier lock vs. Activation Lock explainer, and run a full IMEI check (or the free CTIA Stolen Phone Checker for the US blacklist). For carrier unlock steps, see our AT&T and T-Mobile guides.

Red flags

• Seller refuses to let you insert your SIM or open Settings.
• Only a screenshot is offered as "proof."
• Price far below market "because it’s locked."