Unable to use iMessage and FaceTime on my iPhone XR.

So this has happened a couple of times, with some people that I’ve met over time on the app Wizz, I talk to them by FaceTime and iMessage, then one day, all of a sudden, my messages don’t go through, they don’t call, and the weird thing is I’m under wifi, so my service doesn’t suck, they never blocked me, everytime I call, it went straight to voicemail, and my iMessages turn into text messages, what is wrong???

[Re-Titled By Moderator]