I once talked somebody through restoring a large ORACLE database via mobile phone while I was taking my boat up the River Thames (non-tidal bit thank god). I actually managed to get through 2 locks (it's a good job they were manned) during the process. It was also lucky that the phone was on charge from the boat and that the university was paying for the call !

Such is progress than I can now login on my PDA via the IR link to my mobile phone.