Hi, you can check this: FaceTime Showing “App Requires Specific Features” Error – Explained
The reason FaceTime is showing this error on your iPhone is that your iPhone doesn’t support FaceTime. If you bought your iPhone from UAE or certain other middle east countries, FaceTime will not work. It’s because these countries have banned FaceTime by law. Talking about UAE, it has banned FaceTime and all other VoIP services. They don’t want these apps to surpass its voice call monopoly. Hence, the Telecommunications Regulatory Authority or TRA, which is a sate-run carrier service in UAE, has banned VoIP apps. If you buy a phone from these countries FaceTime will not work. You can not even install the app on your iPhone. However, if you bought your iPhone from any other country, say the US or India, FaceTime will only show this error if you are visiting any of the middle eastern countries where it is banned. That said, you can use a VPN to use FaceTime in this case.