how to know which carrier iphone is locked to?

You can contact AppleCare. They should be able to tell you. See the Contact Us link at the bottom right of every page of these forums.

Please note: this is a user-to-user forum. Sometimes, you need to wait more than a half hour for assistance.

Best of luck.

Three is a network services provider in the U.K., owned by Hutchinson Holdings Co.

http://www.three.co.uk

You said you bought this from an internet store? Did they advertise it as unlocked (not SIM-free, but actually unlocked)? If so, send it back and get a refund. SIM-free just means it came with no contract commitment, but it does not necessarily mean it is unlocked.

Online stores such as CarPhone Warehouse are famous for selling "SIM-free" iPhones, which simply means they sell it at full retail price without a carrier contract commitment. Their iPhones lock to the carrier of the first SIM card inserted.

I would not know - I do not recommend device hacks at all. They generally just lead to problems down the road anyway (for one thing, it will re-lock to its original locked carrier anytime you update iOS or may need to restore it).

Does the internet store not have a return or refund policy? You did say you used an internet store, not some web site like Craig's list or other private sellers forum.

smetijs wrote:

Apple cant help me, three cant help me! WHO CAN?

The place you purchased it for.

Return it for a refund.