Comment Re:No towers in range? (Score 2) 127
Usually, a terrestrial phone doesn't need to do anything much to "look" for a tower, besides keeping its receiver turned on. Towers emit beacons, and if you don't hear the beacon, there's no point in you sending anything - you won't receive a reply because you don't even hear the tower's beacon.
Indeed, many (most? all?) phones won't transmit at all unless they hear the tower's beacon, since it's possible they could have been moved to a jurisdiction where it is not allowed for them to transmit on certain frequencies they would otherwise use.
Of course, keeping the receiver powered to listen for the beacon does use a not-inconsiderable amount of power, so searching for signal will use more power than a phone that is connected to the network and idle.