If we knew that, we could rule the world!
I will have to defer on this a bit, but generally speaking I understand these devices somehow determine signal strength and somehow figure out the best way to phone home. There isn't much you can do to force something to be on that table if that is what you are thinking.
Maybe someone can explain this in more detail.
The other thread I would refer you to is the Zigbee packet viewer thread, especially if you want to see how things are routing. It is an off-board solution that takes additional hardware and software though. Zigbee Packet Sniffer-Cheap &Works
