This paper illustrates an infrastructure based system designed to collect and interpret contextual information in ubiquitous networking environments. Its aim is to support optimised delivery of end-user telecommunication services as well as provide to network self-management functions enriched information about users' perspective on the network performance they get for the services and applications they use. To achieve these aims we exploit collaborative context-awareness amongst end-users and their devices. Per-user and per-network aggregation of contextual information allow the representation of respectively the users' telecommunication environment and the networks' performance status. The paper also contributes a novel decision making algorithm to deliver telecommunication services that match in the best possible way end-user's requirements to current environment resources in terms of e.g. available networks and devices. The resulting model, based on fuzzy logic principles, makes the best service delivery decision given a set of network/device selection criteria and accounts also for relative importance amongst those criteria as well as for the quality of context information.