How to enable wifi calling, with cellular preferred, in lollipop?

In kitkat, I went to wireless & networks, wi-fi calling settings, and then I could choose "wifi preferred," "wifi only," or "cellular preferred."

Now I upgraded to lollipop, and I can't find anything like that. As far as I can tell now, by enabling wifi calling, all calls are forced to wifi. Is there some way to enable wifi calling but only use it when the cellular network is unavailable?