Our analytical cost models have been deployed in numerous countries in the context of regulatory analyses and to support strategic investment decisions. Our models cover the full spectrum of wireline and wireless networks, and the results can be used for cost determination and margin squeeze assessment as well as in evaluating investment plans and business models. The network planning expertise incorporated in our models takes into account factors such as resilience and quality of service and allows us to assess the implications of pursuing particular technical specifications on cost. Our expertise allows us to assess the implications of different network topologies on technical constraints and to understand the degree to which different solutions are likely to be future-proof. We bring this knowledge to our studies for public policy makers, network operators and service providers, as well as to our research work.