Mobile banking has been touted as such a wild success story for one simple reason: mobile phones have penetrated the market in rural areas of developing countries in the last five years more successfully than traditional banks have been able to over the past 100 years. You can travel to any remote village just about anywhere in Sub-Saharan Africa and it is rare that you will find a bank; far rarer that you will find an ATM. (I remember waiting three and a half hours to use an ATM once in Namibia.) But you are guaranteed to hear ringtones.