I am unable to call a friend using FaceTime. Why is this?

[iMore Question]

I'm trying to use FaceTime with a friend in China, who uses an iPad. I've tried iPhone and MacBook Air. Either way it doesn't work. FaceTime says my friend is "unavailable" and my message is not delivered.

By the way, this is the first time I'm trying to use FaceTime. It's also my friend's first time.

 

[kch50428]

https://support.apple.com/en-us/HT204168