The Regional Dialogue on the Information Society (DIRSI) has conducted periodic surveys of mobile telephone tariffs in the principle markets of Latin America and the Caribbean since 2007, using the method of mobile services baskets developed by the OECD. The objective is to follow the evolution of tariffs as markets mature, and to estimate affordability of mobile services for low-income sectors. This estimate is fundamental to the design of universal access strategies, since the level of affordability determines the borders of market efficiency. In other words, without an empirical analysis of the levels of affordability of services, it is not possible to determine which markets are commercially viable without the need for subsidies. DIRSI's surveys, therefore, seek to suport the design of policies that expand the market's borders while at the same time minimising public subsidies.