I have an iphone 6S and of course it is on ios 9.0.2. There is no wi-fi calling option. Why can't whoever writes these articles put a note as to under what conditions it will appear and on what phones.
I was able to activate WiFi calling at home, but at work, where AT&T has a dismal reception, I am unable to activate, probably due to a particular port having to be opened in the firewall. Unfortunately there are NO instructions on their support website, and AT&T support staff has NO clue. It would be great if they published that info, just like Verizon, Sprint and T-Mobile have...