The services delivered by a plurality of providers (SP) towards the users (U) are identified by respective streams of encoded data, for instance MPEG data. The users (U) are provided with respective receiving means (STB) of a generalised type, common to all users. Each user is provided with a user unit (105), preferably embodied in the form of a smart card, incorporating a processing function (VM) able to recognize, load and execute at least one enabling algorithm embedded in the data streams sent by the providers, by exploiting a respective identifying code, also embedded in the delivered data stream, to enable to receiving means, through the user unit (105), to make use of the respective service.