The phone itself wakes up and listens for the base; if it finds it (and the ID matches) then it goes back to sleep. No need to transmit. If the ID doesn't match

The phone itself wakes up and listens for the base; if it finds it (and the ID matches) then it goes back to sleep. No need to transmit. If the ID doesn't match, it pings the new base to register and the network will inform the old base to drop that client. If it doesn't find the base at all it initiates a longer scan to find active bases on other frequencies. Once it finds the best one it has to re-negotiate and auth before the base will start accepting traffic on behalf of that client. Handoff bypasses the delays by having one base communicate to another to bypass the negotiations and the backhaul network automatically re-routes packets when this happens. The clients also get info about neighboring cells and towers which makes handoff easier and faster. As the baseband wakes up in its lowest power mode every minute or two it senses its connected base signal getting weaker while simultaneously one of its neighboring signals getting stronger and during one of these wake sessions it will elect to power up, transmit, and hand-off. Then it can go back into low-power monitoring mode until the next boundary. (This is an extremely abbreviated description of a complex process.) The minimum ping time (let's say it is one hour) is just so the base can prune its client list. When an SMS or call comes in the network doesn't broadcast that to all cells in the country. It knows where your device was last registered and sends it there even. If the base doesn't get an acknowledgement after a timeout period the SMS is dropped / the caller gets voicemail. If your device isn't near that location it should have handed-off on its own which means it is probably turned off or in an area with no signal. As far as I know none of the current generation of cell systems bother to broadcast SMS, phone, or data packets to a wider area near your last known location.