There is an extensive network of buses that covers virtually every road in the country - but this is not an official service as in the west, it is much more interesting than that. Buses leave regularly between major towns, but they do so when they are full, not according to any preset schedule, they are casual by western standards, you may well find chickens on the roof and amiabale people who are curious about who you are and where you come from. Minibuses are getting more and more popular, customers do not have to wait nearly as long for one to fill up and leave.
In rural areas they are infrequent, but still they way that most people cover any distance. They are cheap, friendly and often have great names, Jealous Down, Run Boy, Thanks God and so on are some. Drivers play the music of their choice, just make sure that you get in one that is your choice too. There are bus ranks in the center of all the major towns.