OpenBTS (Open Base Transceiver Station) is an open source software project designed to make it easy to setup and operate your own mobile phone network based on Internet Protocol (IP) technology rather than the traditional proprietary hardware-based systems that are the standard of the telecommunications industry.
The OpenBTS system is particularly suited to remote, rural or off-grid locations. It has been deployed at varied locations including St Pierre and Miquelon, Oaxaca, Mexico and Antarctica. One of the earliest well-known openBTS deployments was at the Burning Man event in August 2008.
In the African context, OpenBTS would be useful for farm settlements, mining sites, disaster deployments and in rural settings, for example, rural Zambia.
OpenBTS has also been used by white hat hackers to test the security of cell base stations.
OpenBTS is developed and maintained by Range Networks which
offers its Network Kickstarter Kit at a base price of $3,300. while this option is obviously out of reach of the average African hacker, there are other cheaper options- particularly if you are proficient with Linux. Here is one example of a 'poor man's openBTS.
You can also download this fantastic (and free) eBook from Range Networks.