There's a pretty reliable way to figure out if you're dealing with a teleport. Watch for sudden emf level 2 readings, and sometimes even emf 5 (25% chance), showing up right where you are without any buildup. One really clear sign is when motion sensors only trigger where you're standing, with no trail leading up to you which usually means they just popped right in.

Drop some salt around your spot and keep an eye out, since regular ghosts will leave uv footprints in it but teleporting ones never do, even when walking right through. Having motion sensors set up in the hallways is super helpful, since teleporting ghosts skip right past them while normal ones trigger a whole path of sensors on their way to you.

The most obvious tell is when you get that emf spike out of nowhere with zero activity leading up to it, especially if you've got sensors laid out and none of them picked up movement along the way. Just remember that regular walking ghosts tend to leave more of a trail, triggering multiple sensors and maybe even making noise as they approach.