I have a fully loaded late 2012 mini, and two thunderbolts attached to it. I noticed tonight when using iMessage that the wifi on my iPhone was off but sending texts via my Mac still worked. I couldn't understand how that was possible. Later I realized bluetooth was still on, so it must transmit through that. So I turned off bluetooth, and sent more texts on my Mac. With no wifi and no bluetooth, my cpu was still sending out legit texts. Only when I shut down my iPhone could I fail to get a message out. So I know the iPhone at least has to be on. My question is how does it send/receive transmissions if it's not wifi or bluetooth? This contrasts with phone calls, which I receive on my Mac and iPad when wifi is on.