With the advent of the future Internet-of-Things, and consequent increasing complexity and diversification of the Enterprise Information Systems landscape, the interoperability becomes a critical requirement for its scalability and sustainable development. This is especially evident in the research and practice of disaster management which involves highly heterogeneous set of institutions and organisations responsible for delivering emergency response services, as they often fail to rise up to the task, with the lack of proper collaboration featuring as a main culprit. Can the current considerations of the interoperability paradigm meet these challenges? In this paper, we define the interoperability as a property of ubiquitous systems. In doing so, we use the anthropomorphic perspective to formally define this property’s enabling attributes (namely, awareness, perceptivity, intelligence and extroversion), with the objective of taking the initial steps towards the Theory of Interoperability-of-Everything. The identified concepts and their interrelations are illustrated by the presented I-o-E ontology.