iPhone X This is a serial number for a product that has been replaced?

[Andeddu]

Thanks
I'm still trying to contact the seller.

If he scammed you he will never speak to you again. Apple will never speak to you unless you are logged into the device via Apple ID. You do not require proof of ownership but you have to be logged into Apple ID on the device.

 

[Intelligent301]

Than

As a former Apple Store employee, I can tell you that iPhone was replaced by a warranty replacement at some point and should have been returned to Apple. That phone shouldn't have been in the wild.
Sometimes this does happen on accident by an Apple Genius Bar employee fat-fingering a serial.
I'd put in a claim to eBay because you will never be able to get service for that device at any Apple store or an Apple Authorized Service Provider.
There are also other scenarios involving cloning serial numbers and Applecare fraud as well.

Thanks.
Do you know why the apple didn't lock this phone after the replacement?

 

[Intelligent301]

Which country are you in?

I'm from Nepal🇳🇵

 

[Andeddu]

Use your Apple ID; nothing bad will happen. People keep telling you this and you keep asking the question.

Stop trying to contact the seller. You posted that they've blocked you so I'm not sure why you think it'll suddenly work.

Put in whatever sim you want to use. If it won't work (cos the phone really is sim-locked; your posts make it seem like you're a bit confused by the situation) then phone every network, apart from your own, and ask them if they've locked the phone and if so to remove it.

Correct. It appears as though Apple locked the device due to the warranty replacement.

 

[Intelligent301]

Ok thanks 🙏

Correct. It appears as though Apple locked the device due to the warranty replacement.

 

[TheHorrorNerd]

Contact Apple. If you provide the receipt they may unlock it for you. No guarantees as you may have unknowingly purchased a stolen, or otherwise illegally obtained device.

They're not going to accept an online transaction. Only a retail receipt.

 

[JPack]

Than

Thanks.
Do you know why the apple didn't lock this phone after the replacement?

Sometimes, it’s not until a while until the phone gets activation locked. Often it’s never. Not sure why. What’s certain is the serial was already used as a replacement, often through serial cloning.