PreQuEst: A Scalable and Proactive Quality Enrichment for Presence Services

The market growth of VoIP infrastructures and services is pushing towards additional facilities to enrich service offer in an open way, thus representing also a differentiating aspect and a competitive advantage for service providers. We claim that the proactive provisioning of estimations about runtime VoIP quality is a crucial facility still missing in VoIP services. For instance, such a facility could be integrated within a Presence Service to inform users of expected quality of VoIP communications towards their contacts before calling them. The paper proposes a novel and scalable solution for proactive quality monitoring, specifically designed for VoIP traffic and based on proper runtime decisions about network partitioning. On top of this monitoring layer, we have designed and implemented an effective and flexible application-level facility for end-to-end QoS estimation. This facility is exploited by an enriched Presence Service in the examined case study. The paper describes the practical experience and the lessons learned in implementing an industrial prototype of the proposal. The prototype is integrated with standard and widespread mechanisms (e.g., SIP Voice Quality Report Event, SIP Answer Mode and SDP Media Loop- back extensions) to facilitate market diffusion and acceptance. First preliminary experimental results show that the proposed prototype achieves accurate quality evaluations and is largely more scalable than traditional end-to-end approaches.