Phone not allowed the sim

What is the exact message you’re getting?

If it tells you the SIM is not supported, the phone is carrier locked. Only the carrier it is locked to can unlock it for use on other networks.

Note that your carrier does NOT exist in both the UK and Turkey. They are different legal entities, even if they have the same name.

In addition, the iPhone 5s is no longer usable as a phone in much of the world. Carriers in most industrialized nations now require at least an iPhone 6 or later.

The SIM card connects you to telephone service by a particular provider. Does the same provider exist in the UK? If not, does your plan from Turkey have international roaming?

waqassamejo wrote:

Well thanks for the brief reply. Actually my phone is not allowed the sim. It’s iPhone 13.

That means it's been blacklisted as it's been reported stolen.