why do I have to power up or connect cable modem, router, VOIP box in a very particular order?

[Racer X]

the router can't talk to your cable modem until it is up and running. Your VoIP box can't connect to the internet and your provider until the router is up and running. Your Powerbook cab't see the internet until the modem sees the internet, then the router can see it, then your laptop can.

It is actually fairly simple if you visualize a string of black boxes. #1 must work before everything after it can.