The Universal Postal Union (UPU)--the International Telecommunications Union(ITU), and World Bank and United Nations (UN) provide data on telecommunications.
Universal Postal Union (UPU)-- the UPU has a large database of postal statistics which is available online. The data base is somewhat more complicated to use than some of the others. The database and instructions for downloading data are available at http://www.upu.int/en/resources/postal-statistics/query-the-database.html .
International Telecommunications Union (ITU) --The ITU makes available data in spreadsheet format on fixed-telephone, mobile-cellular and broadband subscriptions as well as historical communications data in .pdf files. This data is available at https://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspx
World Bank -- The World Bank provides communications data in
time series on its WDI data base WDI Data Base
The Bank has also developed a Digital Adoption Index available at http://www.worldbank.org/en/publication/wdr2016/Digital-Adoption-Index