Whereas abandonment of detailed regulation is widely asserted to be the true way along with the fluctuations of the business models and emergence of IP-based services, there are still remaining unanswered questions about regulatory treatment of interoperability in the converging environment of ICT markets. While interoperability is covered under mandatory solutions under a number of Directives, i.e. Access and Framework Directives, how to understand and reinforce it within converging markets, i.e. new media, telecom and IT markets is unclear on part of regulators as well as many practitioners. While generally interoperability requirements are determined in a disjunctive manner in separate industries, convergence turns interoperability into a common problem against development of ICTs. In fact, not only technical compatibility problems but also competitive failures, economic inefficiencies, and hazards to consumer welfare would arise out of insufficient interoperability. As a matter of...