Modified E-model Based QOS Evaluation of VoIP over a Corporate WAN
For in-service assessing of voice call quality on a data network, measurement methods must have knowledge about network impairments such as delay, jitter and datagram loss. The E-model, finally defined by the ITU-T Recommendation G.107, was developed with such characteristics, providing a single quality-of-service rating value, derived from the relevant impairments, and directly mapped to classical mean-opinion-score values, still requested in most practical situations. In this paper, we propose a practical approach to in-service quality-of-service assessment of simulated VoIP calls on a corporate network that includes WAN (Frame Relay) links as well. We address typical issues with this respect, through investigating real capabilities of corporate WAN infrastructure for supporting VoIP services in such environment.