Thank you for the explanation, makes good sense.
As stated earlier, I too can initiate a FaceTime but the request never reaches the recipient, failing 100% of the time for me so far. I haven't been able to find a fix for this.
I guess at this point Im looking for a helpful diagnosis of why this isnt working for me.
When you try to do FT over Wifi, does it work without any issue?
some people have reported that issue with regular facetime usage.
Try reseting network settings and rebooting