Carrier locked vs unlocked iPhone: how to tell
An iPhone sold by a carrier is usually locked to that carrier until the contract or instalment plan is finished. Put another network's SIM in and it says 'SIM Not Supported'. Sellers often do not know — or do not say — which kind they are selling.
What a SIM lock is
The lock is a policy in Apple's activation servers, tied to the IMEI. When the phone activates, Apple tells it which carriers it may accept. A locked phone accepts one; an unlocked phone accepts any. Because it lives on Apple's servers, no reset or jailbreak removes it.
Check the lock status free
The free Apple SIM lock check reads the activation policy for the IMEI or serial and says locked or unlocked. If it is locked, the free iPhone carrier check names the carrier and country, which is what you need to know next.
If it is locked: what next
Most carriers unlock a phone on request once it is paid off and has been active for a minimum period (60 days for Verizon, 40 for T-Mobile, 60 for AT&T). The previous owner usually has to ask. Failing that, resellers order carrier unlocks through services like ours — the price and time depend entirely on the carrier.
Locked is not the same as blacklisted
A locked phone works fine on its own carrier. A blacklisted phone works on none. Buyers mix the two up, and sellers sometimes count on that.
Run the checks this guide talks about
Questions people ask
The seller says it is unlocked. Should I trust that?
Check it. The free SIM lock check takes seconds and reads Apple's own policy for the phone, which is what the phone obeys.
Will a locked iPhone work abroad?
Only with a SIM from the carrier it is locked to, which usually means roaming charges. For travel, an unlocked phone is the one to buy.
Can a locked iPhone be unlocked permanently?
Yes. A carrier unlock is permanent and survives resets and updates, because it changes the policy on Apple's servers.
What does 'SIM Not Supported' mean?
The phone is locked to a different carrier than the SIM you inserted. It is the lock showing itself.