First thing you should know.
IMPORTANT RESTRICTION FOR iPHONE, iPAD, APPLE TV AND HOMEPOD SERVICE.
Apple may restrict warranty service for iPhone, iPad, Apple TV and HomePod to the country where Apple or its Authorized Distributors originally sold the device.
FaceTime isn’t available or might not appear on devices purchased or used in Saudi Arabia, United Arab Emirates, and Pakistan.
However, with iOS 11.3 and later, FaceTime is available on iPhone, iPad, and iPod touch in Saudi Arabia. And with iOS 12.4 or later, FaceTime is available on iPhone, iPad, and iPod touch in Pakistan. Update your device to get FaceTime in Saudi Arabia and Pakistan.