How can I unlock my iPhone SIM card carrier?

artak208 wrote:

but that phone arrived from USA in Armenia,who can unlock it?

They can be unlocked. However, it really depends. Some are acquired in exchange for a contract or via a payment plan. In that case the contract or payments need to complete before the carrier will unlock the phone. My wife had one before.

It's possible to buy a carrier locked phone at full price. In that case the carrier will likely unlock it. However, if it was a US phone it may only be possible to request the unlocking in the US. I remember when I did it for my wife's iPhone 6s Plus, we had to do it through the carrier's website, and it was aware of where we were. It may not be possible to do that in Armenia.

Go to the carrier and ask them to unlock the phone.

Only the carrier it is locked to can unlock it. No one in Armenia will be able to unlock it.

You will need to find out what carrier in the USA holds the lock.

Return it to the seller and get a refund.

Then AT&T has to unlock the phone.