A recent CGAP brief on Safricom's successful M-Pesa service found that nearly one in three of the informants in Kibera (an informal settlement in Nairobi) kept a balance in their M-Pesa accounts. A survey conducted in 3000 homes in Kenya found this number to be even higher. A majority of users stored money with M-Pesa. Some used the stored value for daily consumption. Others made frequent deposits of "small money" to accumulate a larger amount.

The author of the brief, Olga Morawczynski, a docoral candidate at the University of Edinburgh says: "The fact that M-Pesa is being used for savings illustrates the latent demand for appropriate savings products in Kenya."

However, since Safaricom is not registered as a financial service provider, providing interest on savings is not an option.

"This is a shame," says Morawczynski. "The electronic value stored in M-Pesa is backed by cash in the Central Bank of Africa (CBA). This account is generating a significant amount of interest for Safaricom. What the mobile operator plans to do with this money is yet to be seen. But one thing is clear-it should be poor Kenyans that benefit from the interest on their savings and not Safaricom."

For this to occur, M-Pesa wallets should be linked to accounts managed by formal financial institutions, she says, pointing to the path taken by Zap, Zain's mobile money service.

Safaricom is not alone in shying away from the savings opportunity. This year's Cgap/GSMA Mobile Money Market Sizing Study claimed that by the end of this year there will be 120 mobile money deployments (live or in pilot) around the world.

Says Morawczynski: "There are currently billions of dollars stored under mattresses in the developing world. This means that the market for savings could be just as lucrative as the one for remittances. Perhaps the mobile money industry needs to shift its focus."