<span lang="en">Nowadays, the Critical Communications networks are experiencing the transformation that will lay the foundations for next decades of emergency communications. Although different forums claim for the benefits of different technological solutions, this evolution seems to be driven towards the adoption of commercial radio technologies and mass market devices. Although new standards are being developed by different standardization organizations, the concept of interoperability between Public Safety organizations as a holistic standpoint is still an open issue standards should address in the near future. This paper analyzes the current trends in next generation Critical Communications, and reviews the different efforts carried out by different standardization organizations. It is shown that, although different aspects of interoperability are addressed, an integral interoperability framework is needed. Additionally, the specific area of Operation and Management is discussed as one of the missing pieces. A series of system requirements and design principles are finally provided.</span>