The emergence of new telecommunications technologies, specifically the Iridium satellite network and third generation mobile telecommunication networks, have proven to be problematic for traditional economic theory due to their network characteristics. The presence of network characteristics within such telecommunications markets challenges the traditional economic views of the firm, industry structure and public policy. Significantly, the informational approach is able to provide both meaningful insights and a theoretical basis to examine network markets. Reviewing the fundamentals of network externalities, the determinants of competition and equilibrium in network markets and the models of network externalities provides the theoretical basis for the subsequent application to the case studies, the Iridium satellite network and third generation mobile communication networks, and policy recommendations. Notably, the application to the case studies provides insights into the presence of network externalities in network markets and the implications of the strategic behaviour of economic agents in such markets. The informational approach, applied to emerging telecommunication technologies, creates a set of alternative policy recommendations that recognises the importance of network markets and network externalities.