What stops ghosts from being invited to community lots/called on the phone?

Like the title says. What is it (specifically, which file) that stops ghosts from being socialized with over the phone and computers?

I'm trying to make a mod that lets ghosts be chatted with online (if my unique "commune with spirits" interaction is chosen), but after the Sim picker comes up with all the available ghosts in the game, nothing happens, as I can't actually select one of those ghosts to begin socialising. What gives?