From this page, you can estimate the spending needed to make basic voice telephone services available to the entire population of any country, based on parameters of your own choosing. The model is based on a 10-year horizon: notionally 2006 to 2015.
This model uses a spatial approach to identify areas that have been covered by existing voice networks, classify the remaining areas according to whether or not they are commercial viable and then estimate the cost of building infrastructure to serve these areas. The model distinguishes between:
Market efficiency gap: the portion of the market that can be considered commercially viable, once any remaining regulatory barriers have been removed.
Sustainable coverage gap: the portion of the market that could be operated on a commercially viable basis, once the necessary investments had been funded by public subsidy.
Universal coverage gap: the portion of the market that could never be operated on a commercially viable basis, but would require public subsidy both for investment and operation.
Commercial viability is determined based on the balance of costs and revenues in each pixel of land. The revenues associated with any particular area are estimated based on population density, income distribution, and the assumed budget share going to voice telephony. The costs of serving any particular area are estimated based on the steepness of terrain and the size of the wireless cell site needed to serve the estimated demand, which in turn determine the number of based stations that need to be built. Only the costs of providing a voice signal are considered, exclusive of the handsets and chargers and any other local infrastructure involved in retailing the service