Advanced Metering Infrastructure (AMI) is paving the way for the transition from traditional power grids to the smart grid. This chapter provides details on the overall AMI operation together with a formalization of an AMI as a Service (AMIaaS) concept that is expected to allow Utilities to fully unlock the possibilities brought to the Smart Grid via adoption of the internet of things (IoT) approach. Regarding the ability of Utilities to quickly overview the status of the power grid graphically, the use case is simple, where each of the Utility virtual network functions will gather data either directly from their physical counterpart or indirectly via Virtual Machine Cloud Machine (vMCM). Through AMIaaS, the Utilities will be able to support a transactive energy framework, according to which energy services, like selling or buying, will be the result of instantaneous, traceable exchange of messages (requests/replies) between the involved parties.