I purchased my iPhone XR from Best Buy. when I took it out of the country, I am not able to use it in Armenia because they said the phone is locked. but the Best Buy says its unlocked. Please help me to understand which is correct. Two Iemi number.

Is there a possibility your carrier has not set up Global Roaming? If you are switching to a different carrier, make sure that that carrier supports your phone. To make sure your phone is available for all networks, go to Settings>General>About>Carrier Lock (It should be after the Storage section of "About".) If your device says anything about a carrier lock, that means it is locked to a carrier, and you would need to contact that carrier about removing the Carrier Lock. If they disagree, it is often because the phone is still linked to an available account on that platform. For more information, View "How to unlock your iPhone for use with a different carrier"