When Adam calls what he thinks is Amy Hertz's number, the man who picks up is a curious character. It seems like all the other people Adam encounters on his bike ride show some sense of spooky familiarity with him (at least in hindsight). Most of them try to help him in some way, and even the ones who are a little jerky, like Whipper, seem to exhibit some familiarity. The man on the phone, though, reacts to Adam like he is genuinely frustrated with him, and shows no familiarity at all. In fact, when Adam hears his voice on the other end, he makes the point of saying that it's "not anybody I know" (29.17).
On top of all that, the man is seriously pissed. He mocks Adam in his "gruff, impatient voice" (29.17), and before he hangs up he actually gives Adam some real-world advice (to call Directory Assistance). This guy is actually being majorly inconvenienced by Adam. While other characters linger and stare, the man on the phone wants to get away as quickly as possible. Could this be because he's the only character who is, for lack of a better word, real?