This is a hypothetical map, it shows the distribution of what would be the cost of everyone having a mainline telephone. In reality there are 12 mainline telephones for every 100 people living in the world. In Western Europe there are 57 per 100 people, in Central Africa there are 3 per 100 people.
Mainline telephones are most expensive in regions that are either poor or rich. Telephone costs in regions with medium wealth are roughly a third of the equivalent costs in regions at both extremes. The world average earnings from each mainline telephone is US$630 per year; the regional averages range from US$265 in Southern Asia, to US$2805 in Japan.