I keep thinking about the broken phone and how it may be an analogy or foreshadowing of something else. I mean, yeah it is humorous since every phone has adds that indicate how indestructible they are, yet they break easily, but something about the broken phone scene feels like it is trying to send a message. It keeps being brought up several times by different characters and seems like more time was spent putting that part about the broken phone, screen image of cracks included, into the game (Chekhov's Gun: if you introduce an element into a story, it should have a later scene where it shows up as relevant). Could it indicate that reality is actually not what it is (cracked/fractured/broken)?
Broken phones are often used in analogies of human nature to indicate that life is not always perfect and is often painful and that the holder of a broken phone is mysterious and hard to read (much like a broken phone is hard to read).
A broken phone is also an analogy of a lack of self-care if the holder of a broken phone fails to get it fixed and keeps using that faulty phone. It indicates unresolved mental stress or physical illnesses hidden under the surface.
Null has all of the above since his power is mysterious and hard to read, his introduction to his power is painful and he has stresses that drive him to adapt. In addition, his contact with the Shadow King (Farouk) at the beginning is certainly an indicator that reality may be "cracked" due to the powers wielded by the the Shadow King and potentially by Null himself. I look forward to seeing if that cracked phone makes a reappearance in some form or another later in the game.