M-PESA is probably the best-known mobile money transfer service and one of the few successful business models for such a service anywhere in the world. Over 75 financial institutions in Kenya alone, including banks, microfinance groups, insurance and pension plans, and savings & credit cooperatives (SACCOs), currently work with Safaricom to offer mobile banking to their customers. Most of these institutions offer "deposit only" service over the M-PESA platform (referred to as the M-PESA "rails"). Microfinance institutions (MFIs) also allow borrowers to repay loans via M-PESA. Benefits include reduced operational costs and increased staff efficiency (for retail banks who lose money on low depositors, these are particularly compelling advantages); greater convenience and personal control for customers. Problems to resolve include incompatible software and, thus far, very limited middleware for financial institutions and Safaricom's respective systems; customer data-entry errors, particularly for account numbers; money transfer and reconciliation delays; and lack of transparency on customer fees for M-PESA platform access. (The fee structure is complicated and, because Kenyans are accustomed to paying unusually high fees for all banking and money-transfer services, they are less inclined to demand clear explanations on pricing.) M-PESA is still used primarily as a mobile money transfer service, but an increasing number of Kenyans set money aside in their stored value accounts for savings as well. Banks are quick to point out that these savings are not guaranteed and, without a banking license, M-PESA cannot award interest. For the present, however, many M-PESA customers find formal banking services too inaccessible or expensive, and the advantages of saving, transferring money, and, in some cases, paying by phone are clearly preferable. So, M-PESA is helping to further financial inclusion, but it is also creating what one expert calls "low-equilibrium financial inclusion...poor quality, high cost, and potentially high risk inclusion".