278 ITU‐T's Technical Reports and Specifications 2.5.4 Solution High Level Details There are different models of deploying Open Access Networks as shown in the diagram below but Model‐3 is the most common in Middle East. Figure 45 – Models of deploying Open Access Networks In this diagram: Infrastructure operator (IO): who operates utilities such as ducts and wire poles. Network operator (NO): who operators resources such as optical cables. Communications operator (CO): who operates active equipment, such as optical line terminals (OLTs) and optical network terminals (ONTs) on the network. Retail service providers (RSPs): who retail services such as data, voice and video services. In the model‐3, Communication Operations (CO), Network Operations (NO) and Infrastructure operations (IO) are managed by the Main Network Owner and only Services are provided by the external Retail Service Providers. This brief study focuses on CO part in the following sections. The most common Open Access Network CO architecture for the Smart Cities is shown in the Diagram below.