Neves, FilipeCardeal, SimãoSoares, SalvianoAssunção, PedroTavares, Filipe2026-01-262026-01-262011F. Neves, S. Cardeal, S. Soares, P. Assuncao and F. Tavares, "Quality model for monitoring QoE in VoIP services," 2011 IEEE EUROCON - International Conference on Computer as a Tool, Lisbon, Portugal, 2011, pp. 1-4, doi: 10.1109/EUROCON.2011.5929300.978-1-4244-7486-8http://hdl.handle.net/10400.8/15512This paper presents a no-reference model for monitoring the voice quality experienced by users in VoIP services. The proposed model is based on the E-Model, which is adapted from Recommendation ITU-T G.107 for this purpose. A calibration function was determined for relevant codecs under different packet loss conditions. Extensive field testing was carried out to validate the proposed model at PT Inovação Labs (Portugal). The results show that the mean opinion score (MOS) obtained from the proposed model match class C2 of conformance tests defined in ITU-T Recommendation P.564. The QoE model described in this paper was implemented in a VoIP QoE probe and is currently fully operational at Portugal Telecom.engconference paper10.1109/EUROCON.2011.5929300