FaceTime application not available

You should check with your service provider to see if FaceTime is supported.

From Apple Support:

You might have issues using FaceTime for one of these reasons:

• FaceTime Audio or Video calling might not be available for all countries, regions, or carriers.
• FaceTime isn't available or might not appear on devices purchased in Saudi Arabia, United Arab Emirates, and Pakistan.
• Call forwarding isn't supported by FaceTime.
• Phone calls end when switching to or answering a FaceTime call.
• You can't switch from a FaceTime call to a voice call, or from a FaceTime Video call to a FaceTime Audio call.