Are Kenyans still using Airtime as currency?

photo by Global Envision

According to the Economist, there are some Kenyans who are still using pre-paid mobile-phone units as currency.

Airtime minutes are being used as a de facto currency that can be transferred between phones,exchanged for cash with dealers who rent out phones,or bartered for goods and service, and especially useful for settling small debts.

Why do people still use mobile phone airtime as currency instead of mobile money? It is stable,anonymous and free.

Read: The use of pre-paid mobile-phone minutes as currency