I live in Somaliland. The top telecom company here, Telesom, has a mobile money transfer service here called Zaad. Basically, people setup a Zaad account at their local Telesom office and exchange their physical currency for credit in their Zaad account.
They then buy stuff at shops or send money to folks right from their mobile phone using a USSD interface. The USSD interface works like this:
1. Dial *888# 2. A prompt appears on your mobile phone. The prompts could be a menu, a request for a password or whatever 3. The user clicks reply (a context menu appears on the phone) and types in a reply. 4. Go to no. 2 until the transaction is complete.
Zaad has exploded in growth in the 2 or 3 years it's been around and has freaked out a lot of other businesses here who suddenly got a scary new popular competitor. The best part of Zaad is that you don't need a smartphone or internet connectivity to use it. Literally any mobile phone works with it. Even an old-school Nokia 3310.
Telesom isn't the first country to come up with this idea. If I'm not mistaken, the first company was a Kenyan company called Safaricom and their product is called M-Pesa. It has 6 million subscribers using it.
Imagine 6 million folks sending transactions and getting a tiny cut out of every transaction. M-Pesa is huge.