Simply follow this tutorial to get Facetime if it is restricted in your iDevice as some countries have it disabled as default.
Your device needs to be jailbroken.
1. First, open up Cydia.
2. Navigate to Manage, Sources then tap on edit and Add Source.
3. Enter this source : http://apps.iphoneislam.com
4. Click on save and let it refresh your repositories.
5. When done, search for Facetime Hacktivator and install it.
6. Respring your device, open up Settings and set up your Facetime. :)