In one of the presentations by Andreas Antonopoulos on Bitcoin, he said that "there are 6 billion people in this world who have no banking facilities, who live in places where they have cash or barter based societies. In these places, where banking services will never reach and the nearest bank is 100 miles upstream, where the only form of technology is a Nokia 1000 feature phone, every phone become a banking service"
My question is this. In a scenario as described above, how would one transact his/her hard money or the farm products (say bananas) using a basic phone without any banking facility? In other words, how will one convert his "bananas" to bitcoins?