"The question was: Could we harness a simple phone as an educational tool?" she said.

Aker and her team developed a literacy class centered around mobile phones and included lessons on how to use handsets as well as how to convey basic written information. After eight months, the farmers achieved elementary-school education levels in reading and writing, Aker said.

Basing the class on mobile phones "allowed the adults to learn more quickly and learn skills for use outside the class," she said.

In addition to obtaining information, mobile phones can help business owners improve inventory and foster jobs, Aker said. Rural shop keepers can call suppliers and order goods instead of waiting for them to approach the store. The use of pre-paid phones has spawned side businesses vital to keeping the devices working, such as phone charging services and air time vendors.

Mobile carriers have also realized that handsets can fulfill many roles. In 2007 Safaricom, which offers phone service in Kenya, launched the M-Pesa mobile banking service for people to pay back microloans.