ITU‐T's Technical Reports and Specifications 929 were not following a broad and horizontal strategy, and sector‐specific vertical approaches were based on separate infrastructures, not interworking with each other while often physically overlapping. None of these models can satisfy the complex and comprehensive requirement of future urban management and sustainable development. Therefore, the original digital systems, as well as the traditional ICT standards, should be improved or redesigned from a broader and higher level perspective, to achieve the transformational impact that smart sustainable cities ought to bring about. The development of SSC standards can be accomplished through cooperation among standards organizations and the adaption of existing standards, fulfilling the principle of openness, compatibility and versatility. 4.2 Challenges In considering the work required to develop SSC standards, it is important to take two key issues into consideration: In addition to ITU‐T, a number of other important standards bodies are working to scope out and develop SSC standards. While international SDOs including ITU are already developing standards in many of the key technology areas related to smart and sustainable cities, those standards may not necessarily reflect the complexity of dealing with a smart and sustainable city as a system of systems, and the specific challenges that this brings. Development of broader perspective and coordination and collaboration among SDOs will enable earlier and more effective development of ICT infrastructure. These two factors indicate the following challenges regarding SSC standards that need to be addressed: The necessity to fulfil the needs of city sustainability in social, economic and environmental aspects. The need to ensure interoperability between different city systems. The need to take into account the challenges of complex organizational requirements, including interfaces between the public sector and commercial organizations, and among commercial organizations. The need for the city to be able to manage issues such as privacy, cyber‐security, resilience, and data flows on a whole‐system basis. The need of non‐specialist city leadership to be able to understand the many, complex and interrelating ICT issues relating to the move towards a smarter and more sustainable city and how to put together the right portfolio of standards requirements to ensure that their projects are able to succeed. The need to ensure that standards being developed by study groups within ITU take into account the requirements of smart and sustainable cities. The need to ensure consistency with SSC standards being developed by other international standards bodies. The need to ensure standards organizations are connected with basic (non‐ICT) technical areas to understand their needs and develop proper solutions.