There is one thing that I'm not sure of Globaliser. Do I take it that a mobile phone is able to adjust the output power of a signal in accordance to the proximity of the receiving station? So a closely located picocell would draw a weaker signal than a more distant cellular mast. If that is so then I didn't realise that a cell phone had that capability. That would make sense as then when on the ground it would only locate the nearest mast rather than bang out a signal at max strength only to possibly be picked up at several masts.