Smirking, he picks up the phone again, and dials a number — tap! tap! tap! “Hello, again,” he says, amused. “Of course, what I meant to say was ‘Aeneadum genetrix, hominum divomque voluptas.’ Rookie mistake! Yeah! I know, right?!”

Another rookie mistake: it's divum, not divom.

EDIT: Turns out that it wasn't wrong, just a strange form.

Smirking, he picks up the phone again, and dials a number — tap! tap! tap! “Hello, again,” he says, amused. “Of course, what I meant to say was ‘Aeneadum genetrix, hominum divomque voluptas.’ Rookie mistake! Yeah! I know, right?!”

Another rookie mistake: it's divum, not divom.