As mobile phone sales have exploded and handset prices have tumbled, even people in the poorest parts of the world usually either own a mobile phone or have easy access to one in their community. The latest estimates from CGAP suggest that by 2012 there will be 1.7 billion people who have access to a mobile network but not a physical bank, and that the developing world's mobile banking sector may be worth US$5 billion by then. Could banking be the way forward for network operators who don't just want to be "dumb pipes"? And could this be a key weapon in the war against poverty?