Notification bar mystery icon

[AC Question]

The icon looks like a phone receiver laying on the bottom with signal strength curve lines on top. And it has the red circle with diagonal slash through it (like a "no" sign has. If it's not a Samsung icon, should I suspect some app?

 

[hallux]

Sounds like something to do with WiFi calling. Is it possible it's not enabled on your plan or your WiFi network doesn't allow it to work for some reason?