I've gotten it even when no-one in my active family died. I guess the only requirement is that someone with whom your sim has a high relationship dies, be it an active family member or a townie. After that you have a chance for the phone call.
For example, my sim was good friends with Cornelia Goth, and after her death she got the phone call. I accepted the opportunity but did not use it. I saved it for later - you can do that! So when you want you can use it to resurrect any ghost with whom you have a high enough relationship. I ended up with 3 sims with the opportunity, as they too were friends with Cornelia (I assume they got it due her death). So it's not that uncommon, at least I get it quite frequently!
But now that I think about it, they were distantly related to the Goths. So maybe any townie friend doesn't count? Anyway, I used the opportunity much later to resurrect someone else.
Being friends is not enough, you need to have the grave in your inventory. So I guess resurrecting the ghosts from the graveyard is only possible if you get a hold of the grave. I think you can steal it with a kleptomaniac sim... but I never tried befriending them so I don't really know all the options.
