I don't know. The way I've heard it, before we, that is, before Lachesis's imPorts arrived here, she was able to connect to the Porter in this universe. She made it possible for it to bring us from that world—made sure this world would be expecting us. Since we've arrived, though, there hasn't been a trace of her... but that doesn't necessarily mean she's gone, or that some other intelligence is controlling that machine.

Why it's bringing in people from their own worlds, that aren't on the verge of destruction... I don't know that, either.