Well it's worth keeping in mind that the ringing you hear is coming from the cell-phone tower / service provider / etc. and not the called person's phone anyway

Well it's worth keeping in mind that the ringing you hear is coming from the cell-phone tower / service provider / etc. and not the called person's phone anyway whether or not they're on the network. I don't know the specifics on how a tower determines if a phone is or isn't on the network at the current moment, but I don't think it's unreasonable to imagine that the service provider wants to appear to be fast, and thus starts playing the ringing tone immediately after the call is placed (Rather then wait). This definitely happens in the US, I can attest to that, I'm surprised to hear this doesn't happen everywhere else. At the same time, it's not like it really makes any difference one way or the other. It is a curious thing though. It seems to be like computer networks, where Ex. if you ping a non-existent address you just sit there waiting until a sufficient amount of time has gone by that you decide they aren't on the other side.