Yes, you're correct about the meaning. It means that someone is not really trying, or is not putting in a serious effort. For example, imagine an actor who normally gives good performances in movies, but when you watch him in his newest movie, you get the feeling that he just wasn't very invested in it. The actor performs his scenes and speaks all the dialogue correctly, but he doesn't really put any emotion into the performance. In this case, you might say that the actor was "just phoning it in." He did the work he was supposed to do, but didn't make a serious effort to do it well. It's not a very common phrase, but I've heard it occasionally. It can also be used to describe someone who thinks they're so good at something that they don't even need to make an effort anymore. Instead of really trying to do a good job, they just do their job in a lazy or indifferent way, assuming that everyone will be happy with whatever they do.

This is a common enough expression, and yes it does mean to not treat something seriously (sorry but unseriously isn't a word). Imagine someone not showing up to work, but phoning the boss to say they are there. They aren't giving what they should.

Did you see it in a sentence somewhere? If so, could you write it in? It’s out of context so it’s hard to understand what that person meant. I would guess it means to call for help.

❤️

I think I have heard this but don't know what it means. So to me it's not a common phrase. Never heard it in a conversation but maybe a movie or something like that once