We can't unlock this device for you because we didn’t sell or activate it.
I bought an iPhone 12 while in the US. I asked the store if the phone is unlocked and they mentioned the iPhone is on US Reseller Flex Policy and that I should be able to use it with any carrier. So I inserted my AT&T SIM and activated the phone. It worked fine. But then I traveled out of the state and I tried to apply for an unlock of the device so I can use it in the other country. I applied on the AT&T website but then it keeps returning an error "We can't unlock this device for you because we didn’t sell or activate it." I really don't understand cos I did activate the phone on AT&T. Please help.