Wifi calling enabled, but not working at all

[AC Question]

I'm using a ZTE ZMAX Pro on MetroPCS, and on top of other issues, the wifi calling is being a pain. The phone shows that it's enabled just fine, but when I try to send a text, it immediately tells me it failed. Calls don't even go through. I've tried several reboots, and obviously nothing came of it. Any ideas are appreciated.