The idea that mobile phones bring economic benefits is now widely accepted. In places with bad roads, few trains and parlous land lines, they substitute for travel, allow price data to be distributed more quickly and easily, enable traders to reach wider markets and generally ease the business of doing business. Leonard Waverman of the London Business School has estimated that an extra ten mobile phones per 100 people in a typical developing country leads to an extra half a percentage point of growth in GDP per person. To realise the economic benefits of mobile phones, governments in such countries need to do away with state monopolies, issue new licences to allow rival operators to enter the market and slash taxes on handsets. With few exceptions (hallo, Ethiopia), they have done so, and mobile phones are now spreading fast, even in the poorest parts of the world.