Facetime on phones meant for several countries in the Middle East and Egypt will only work when using one of the authorized carriers in said countries.
If used on a different carrier or taken outside the area, Facetime may be unavailable and cannot be installed or un-restricted.
Wireless carrier support and features for iPhone in Africa - Apple Support
FaceTime might be unavailable if your device originates from Egypt and becomes unlocked or is used in another country or region.