Until the mid-1990s, telephones in poor countries were mostly in cities. Some African countries had only a single telephone for every thousand people.
Since then, mobile telephone networks have spread rapidly in most low income countries. But what difference do telephones make to people's lives? And are they important for development?
This brief summarises an important new study by leading telecommunications researchers – conducted in rural areas of India, Tanzania and Mozambique – which has found some unexpected answers to these questions.