Mobile buying booms in US, banking in India

"In many parts of the developing world, mobile is the most common piece of infrastructure that exists," Beccue said. "In many places, there are more mobile phones than there is running water or electricity."

In late 2007, Safaricom, the dominant mobile operator in Kenya, started a program called M-Pesa. To use it, Safaricom customers give money to the local agent for the carrier, who may be the corner shopkeeper. That money can be used to prepay for phone service but is also used like a bank deposit. When the consumer wants to pay a friend or merchant who is also a Safaricom subscriber, he simply sends an SMS message authorizing the payment. The carrier knows about the transaction and can verify it because it controls the SMS system. The recipient gets the cash in his account and can pick up the cash from another agent of Safaricom.

M-Pesa has taken off partly because a vast majority of Kenyans are Safaricom subscribers, Beccue added. So far, such point-to-point payment systems don't work across carriers. But despite that limitation, the number of people using such systems worldwide roughly doubled last year, from 27.6 million in 2008 to 55.4 million in 2009, according to ABI.