Book excerpt: This book investigates at both the micro- and macroeconomic levels the impact of mobile phones on poverty and inequality in developing countries. To gauge the effects of mobile phones on these aspects, the author refers to the standard concept of technology adoption and also analyses the actual utilization of mobile phones as a means of communication and the degree to which they have supplanted fixed-line phones. Readers will learn why the substitution effect is stronger among poor than rich users and why the benefits of some mobile phone projects are confined to the local or village level, while in other projects the gains can be felt throughout the economy as a whole.