M-Paisa (AKA M-Pesa) is an extremely successful and efficient scheme for managing micropayments and electronic banking using SMS. In more developed and stable places, the system uses ATMs as end-points; in rougher conditions, "human ATMs" take cash in and pay it out. It's so successful that the Afghan National Police in Kabul are paid by M-Paisa transfers; the system also allows person-to-person payments in the form of mobile airtime credit that can be converted to cash.
Here's how it would work in Afghanistan. Say Abdul in Kabul wants to travel to Herat, but he is afraid he might be robbed along the way — a very reasonable suspicion. So Abdul sends 400 rupees to himself, or to his friend Haji who lives in Herat. Abdul gives his local money agent the 400 rupees which is entered into his account. Abdul can then travel with no cash. When he gets to Herat, he goes to the local agent, and gives his number and pint to redeem his cash. In Kenya, which is a little more developed, the agent can be a corner ATM. The recipient types in their phone number and PIN and out comes the cash.
M-Pesa takes a cut, but it is one third of what a Western Union type of money transfer would charge, and a lot cheaper than having a bank account. You can also send cell phone "air time" to a recipient instead of cash.
This kind of mobile banking has also been a source of livelihoods for agents, which start out simply as human-ATMs but can eventually grow into offering more banking-ish services.
(via Command Line)
