The Digital Opportunity Index is a way of measuring access to ICT. As described below, it is calculated on a country-by-country basis using several indicators, but apparently does not take localisation into account. It results in a number between 0 and 1. The DOI for Africa as a whole is 0.20.
"DOI is a composite index based on 11 core ICT indicators. ... [It] is at present the most extensive ICT index providing an internationally-agreed benchmark of the status of ICTs around the world." (Wikipedia)
"[T]he Digital Opportunity Index (DOI), ... has been developed by the Digital Opportunity Platform, whose members currently include ITU, United Nations Conference on Trade and Development (UNCTAD), the Korea Agency for Digital Opportunity and Promotion (KADO) and the Ministry of Information and Communication of the Republic of Korea." (ITU 2006)
"The DOI was endorsed by the World Summit on the Information Society in the Tunis Agenda for the Information Society (para 117) as a tool for mapping of digital opportunity worldwide." (Wikipedia)
"The core ICT indicators represent international agreement on the main statistics to be used for analyzing the Information Society. Eleven indicators — of which six have a fixed line orientation and five are geared to mobile — have been selected for the DOI." (ITU 2006)
The indicators include:
International Telecommunications Union (ITU). 2006. World Information Society Report 2006. Geneva: ITU. http://www.itu.int/osg/spu/publications/worldinformationsociety/2006/wisr-web.pdf
Wikipedia, "International Telecommunication Union: Digital Opportunity Index," http://en.wikipedia.org/wiki/Digital_Opportunity_Index#Digital_Opportunity_Index