PARIS — Mobile payment systems have become an important financial tool in the developing world, but experts say network operators need to offer more than just person-to-person transfer features to create a compelling business case.

Nick Norman, the commercial manager for the U.K. research firm Consult Hyperion, said mobile phones are emerging as a financial lifeline for the 15% of the world's population that lives on $1 or less per day, and such services offer a significant business opportunity.

"If you are a vendor or" carrier, "this is a place to play," Norman said here Tuesday at the Cartes and IDentification conference.

The best example is in Kenya, where the M-Pesa service now has 7 million subscribers and processes $2 million per day in transactions, averaging about $20 each.

Consumers with mobile phones use the service to send each other money, and can load funds into their accounts or convert the stored value into cash through a nationwide network of agents.

The Kenyan carrier Safaricom Ltd. and the U.K. wireless company Vodafone introduced M-Pesa in 2007 with help from the United Kingdom's Department for International Development.

Norman said the M-Pesa service has replaced such traditional, and inefficient, transfer methods as handing an envelope of cash to a bus driver and hoping the money reaches the intended recipient in another location.

But basic transfer services might not offer a significant return to network operators. Mobile phones "must be able to do other things besides social payments," said Stephen Rasmussen, the technology program manager for the Consultative Group to Assist the Poor, or the networks will remain largely donor-subsidized efforts that produce little revenue and generate scant involvement from businesses. CGAP is a Washington research group that focuses on financial services in the developing world.

Those additional services could include bill payments, which M-Pesa supports, or offering interest to encourage people to use their phones as electronic savings accounts, Norman said. Governments and aid agencies are usingmobile phones to transfer welfare funds to people in need, he said.

"People want more [services] once they get into it," Rasmussen said. He said that though consumers are interested in earning interest through mobile phone networks, some governments might frown on the practice because the technology is starting to move ahead of banking regulations.

Meeting those demands could require partnerships between mobile operators and banks, Rasmussen said.

A successful mobile payment effort for consumers also needs an extensive network of agents who can convert electronic credits to cash, he said. "You need distribution for cash-in, cash-out," Rasmussen said. "Poor people don't want just electronic money."