Evaluation of VoIP quality over the Pakistan Internet exchange (PIE) backbone

This paper assesses VoIP quality over the Pakistan Internet exchange (PIE) backbone between major cities of Pakistan. Passive measurements for voice calls in the presence of background Internet data traffic for different speech codecs such as the ITU-T G.711, G. 723.1 and G.729 were carried out. Interpacket delay and jitter were measured over the PIE IP/ATM backbone and the corresponding inter-packet delay densities were calculated for evaluating the perceptual quality of computer telephony calls using the ITU-T G. 107 E-model. The transmission quality (R-factor) and resultant mean opinion scores (MOS) were calculated for both backbone and access links of ISPs. The study highlights the growth of VoIP as a significant component of the PIE backbone traffic in Pakistan as well as reconfirms the presence of congestion hot spots in the access links.