Adding this could be a great way to implement a message system, it's basically a physical phone that replaces some of the menu options!
So you can message people on your friends list that are online. You can change your avatar from there and also set a message tone when you get a message etc
I think that this will be an awesome addition and will allow vrchat to become even more immersive! Plus it will help mutes communicate more thoroughly if we add a text to speech option.