ITU‐T's Technical Reports and Specifications 159 Application layer: The application layer includes various applications that manage SSC and deliver the SSC services. OAM & P & security framework: This layer provides the operation, administration, maintenance and provisioning, and security function for the ICT systems of SSC. The multi‐tier SSC ICT architecture from communications view, emphasizing on an information flow perspective (illustrated in Figure 5) contains the following layers: Users layer: It organizes SSC service end‐users into groups from both the demand and the supply sides; Presentations layer: It contains the user interfaces (web, apps, voice commands etc.), which stand between end‐users and SSC services; Applications layer: It contains all corresponding software applications that realize the SSC services; Business layer: It consists of the business processes, which lie behind each smart sustainable city service execution; Communications layer: It contains the above mentioned networks, over which the SSC services are performed and transactions and data flow are realized; Data layer: It contains the data and file repositories, where data are created or retrieved; Sensing layer: This layer consists of terminal node and capillary network. The terminals (sensor, transducer, actuator, camera, RFID tag, barcode symbols etc.) sense the natural environment where the smart sustainable city is located and the corresponding hard infrastructure and utilities (water, transport etc.). It provides the superior 'environment‐detecting' ability and intelligence for monitoring and controlling the physical infrastructure within the city. The capillary network connects various terminals to communication layer, or directly to data layer and/or application layer providing ubiquitous and omnipotent information and data. Detailed discussions on ICT Architecture and Architecture Framework, as well as security aspect of Smart Sustainable Cities is available in deliverables SSC‐0345 “Setting the framework for an ICT architecture of a smart sustainable city” and SSC‐0090 \"Technical Report on ICT Infrastructure for Cyber‐Security, Data Protection & Resilience\", respectively of the Focus Group on Smart Sustainable Cities (FG‐SSC). d) Smart Infrastructure and Integrated Platform Investing in ICT infrastructure constitutes a critical component of a city's transformation into a SSC. This technology can provide crucial information for city managers to increase the efficiency in urban services, improve the quality of life of citizens, ensure a tangible economic growth, strengthen prevention and management of natural disasters, simplify physical infrastructure used in some services (e.g., mobility, energy), and improve the city's sustainability. In order to reduce as much as possible, this initial investment, cities can adopt the notion of \"convergence\", by using pre‐existing networks to establish new ICT infrastructure. The first step for introducing ICT technologies in cities is to consider all stakeholders involved in this process. In terms of interconnected infrastructure, the most relevant stakeholders will be the telecom operators, ICT providers, financial institutions, utility providers, emergency services, local institutions, NGOs, regulators, funding bodies, universities, as well as Research and Development (R&D) institutes. The ICT infrastructure of SSC contains a vast array of technologies. The most important ones, grouped in three categories, are listed in Table 2: