Telecommunications are in permanent and constant change. The arrival of 5G brings new use cases to the table, wich drive the standarisation and where the efforts shall be directed. Also, Vertical Industries are demanding better performance in terms of network flexibility and computation power to Infrastructure Providers, and even vertical applications are requiring more complex scenarios (e.g., in Industrial, Immersive Media and Real Time Communication applications). Vertical industries do not only require a reliable, fast platform, but also to reduce on time-to-market and capability to manage Quality of Service (QoS) for certain applications. ETSI Network Functions Virtualisation (NFV) ISG is doing an effort to give solutions to these new problems aroused. In NFV nomenclature, these applications are abstracted by a concept called Network Service. Some of these Network Services might be instantiated in complex scenarios, which must be connected across a Wide Area Networks (WAN), where recently Software Defined Networks (SDN) have been acquiring more importance, reducing Capex and Opex costs for WAN providers but also speeding up the process of network configuration, where Open and well-defined APIs are becoming a key to success. To solve the problem of instantiating services across a WAN, there exist the concept of WAN Infrastructure Manager (WIM), a component defined in ETSI NFV architecture and which currently Orchestration Platforms developers are bringing up some solutions with. WIM(s) communicates directly with the NFV Orchestrator, the main component governing a NFV Management and Orchestration Platform. In this respect, this thesis has developed a solution within 5GPPP 5GTANGO project to extend SONATA NFV platform in order to be used to deploy network services over multiple Virtualisation Infrastructure Managers (VIM), which are interconnected through one or multiple WIM(s), using ONF Transport API (T-API) definition as WIM Southbound API Interface. Moreover, these instantiation has been validated and it has been analyzed the benefit of using a Point Of Presence (PoP) closer located at the 'edge' for instantiating a QoS reliant Network Service. T-API has been also extended in order to be used in application connectivity services, allowing an extension of what is called in SDN 'flow matching'. Thus, the main output of this thesis is going to be included in new SONATA Service Platform release 5.0, and furthermore is going to have a critical importance to give functionality to one of 5GTANGO project pilots
