Economists and policy makers say mobile agents like Ms. Yashwant — who also are employed in countries like Brazil, Mexico and Kenya — represent one of the most promising ways to help the rural poor save and protect their money. Many people in India who do not have bank accounts, for instance, buy gold necklaces or simply keep cash in their unlocked homes.

“This is something that could be powerful,” said Abhijit V. Banerjee, an economist at the Massachusetts Institute of Technology who wrote “Poor Economics: A Radical Rethinking of the Way to Fight Global Poverty” with Esther Duflo.

The banking agents enable the poor to easily save money they otherwise might be tempted to spend, Mr. Banerjee said. And when times are lean, people could withdraw money they had saved, instead of borrowing cash at high rates of interest. The accounts earn currently earn 4 percent annual interest, which is standard for savings accounts in India. There are no maintenance fees or charges for deposits or withdrawals.

“It’s true that this will not make them rich,” Mr. Banerjee said, “but it will make them less likely to face starvation someday.”