Since 2002 an ongoing programme has ensured the installation of reference stations in several African countries. Currently, the Interregional Satellite Based Augmentation System in Africa (ISA) comprises 10 stations: in Chad, Cameroon, Central African Republic, Congo, Ethiopia, Kenya, Zambia, Namibia, and South Africa. This network provides corrections and improvements to the GPS signals all over Africa. These corrections are similar to those available in Europe. All these stations are linked to the EGNOS test bed located in Hönefoss, Norway.