As one of the fastest-spreading technologies in history, the mobile phone has been transformative for the billions of people in the developing world who never had a landline or an Internet connection. One of the most unexpected benefits is its ability to deliver banking services.

Veronica Suarez, like some 2.5 billion other adults on the planet, has no bank account of her own. Suarez and her husband run a small grocery store in Quito, Ecuador, a city of about 1.4 million people on a plateau ringed with dormant volcanoes. In the past, she would often spend half a day traveling to pay bills in cash. But since June, she has been testing a mobile banking service called Mony, which is run by the Panama-based startup YellowPepper Holding. Now she can simply type out text messages that zap payments to the phones of the delivery men who bring cases of Coca-Cola and boxes of vegetable oil to her shop. That could enable her to save travel time, reduce the risk of getting robbed, and run her business more efficiently.