Some blogs about experience of building GSM network at africa with LOW investment

http://blog.ted.com/2007/07/incremental_inf.php
http://www.ethanzuckerman.com/blog/2007/07/02/incremental-infrastructure-or-how-mobile-phones-might-wire-africa/
http://www.latimes.com/news/opinion/la-oe-easterly6jul06,0,6188154.story?coll=la-opinion-rightrail
http://jchyip.blogspot.com/2007/07/incremental-infrastructure-in-real.html