For consumers in developed markets, using a mobile phone for banking services is a smart add-on to a bank's branch network. But to people in the developing world, the arrival of mobile banking - or m-banking - is potentially revolutionary. If money is an economy's lifeblood, improving its circulation plays a critical role. Many Africans living in rural areas, for instance, rely on money sent home by members of their family who work in towns and cities. But getting that cash to a village that could be hundreds of miles away is a tricky business.