What I can tell you from my experience in the Gambia is that there many people have cellphones (not smartphones), but most have 2 or 3 because provider have lower rates when calling to the same provider, so one phone for Qcell, one phone for Africell,... Not sure if it's like that in many other places, there is a lot of tourism on the coast and returning tourists often bring their old phones to give to the locals.