17 million Bangladeshis (10% of population) using bKash a form of mobile payment. Individuals can transfer money between each other through a network of merchants around the country. The sending party can go to a merchant and pay in cash. Then the merchant sends a text message to another merchant close to the receiving party. The receiving party goes to the merchant close to him to collect.
In a country where less than 30% of its 160 million people have bank accounts this payment method has the opportunity to address critical market failures. See the case of mPesa in Kenya and other countries in Africa which are pioneering mobile payments.
The merchant network in countries with large underbanked populations have for many years shifted to become a powerful financial services and telecommunications providers.
More on WSJ.