This article offers a research tool for comparative studies of digital communication systems. It brings together the fields of infrastructure studies, Internet governance, and political economy of the Internet with the tradition of systemic media analysis and argues that existing frameworks are inadequate for capturing regulatory and power structures in a complex digital environment. In the article, we develop a framework for conceptualising and mapping the components of digital communication systems--the DCS framework--and operationalise it for standardised measurements by outlining twelve key indicators that can be analysed using empirical data from a number of existing databases. The framework provides a basis for measuring and comparing digital communication systems across national or regional contexts, and thereby developing new typologies for how to understand structural differences and similarities.