The Global Financial Inclusion Database, or Global Findex, has found only 3 percent of the population in the rest of the world take advantage of money transfers through mobile phones.

In sub-Saharan Africa, take-up of mobile money services, pioneered by Kenya-based Safaricom's M-Pesa service, has been boosted by the fact that traditional banking is hampered by transportation and other infrastructure problems.

"Money transfers through mobile phones is a form of increasingly nontraditional banking that often doesn't require users to travel or set up an account at a brick-and-mortar bank," according to a statement issued by World Bank.

"Such mobile banking allows account holders to pay bills, make deposits or conduct other transactions via text messaging," the World Bank noted. Kenya, where 68 percent of adults report using a mobile phone for money transactions, has seen particularly impressive growth in this market.

According to the study, three-quarters of the world's poor do not have a bank account, not only because of poverty, but also because of the cost, travel distance, and the amount of paperwork involved in opening one.