Calls won’t work with one person

When the problem started I would FaceTime the person, they’d answer and be able to see and hear me but I can’t see or hear them. I just get a screen with a name. Their voice calls seem to reach my phone sometimes, but not other times. And if they FaceTime me it won’t even ring on my end. Today I was told that they can’t even receive texts from me now. I favorited the person and even blocked and unblocked them to see if it did anything. It’s been happening for a few days now. We had an issue every few days where there would be a “join” icon in their texts.