**3.4 Discussion of E-Model optimization results**

This chapter utilized the E-Model to assist with the selection of parameters important to assure the QoS of VoIP in IMS Networks. These parameters include the voice coder, allowable packet loss and the allowable background link utilization. It was based on the concept that maximization of the link usage with respect to the number of calls which is important to the user. It was shown that an optimization of the E-Model is possible and useful. Table 13 reviews the total results of the optimization problem.


Table 13. The total results of the optimization problem.

All of the three cases found that G.723.1 is optimal depending on the Circumstances. G.723.1 looks more favorable due to the fact that G.723.1 uses less bandwidth per audio stream. In case 2 , G.723.1 with 0.5%, 1% and 1.5% packet loss was optimal but with packet loss 2 % it was not feasible and G.729 was the optimum coder. In case3 , G.711 coder was selected in case of background link utilization of 90% but in all other cases till 95% G.723.1 was the optimal coder giving the maximum number of calls with R Value more than 70%. The ability to analyze various coders, delay, packets loss and the effect of background link utilization is vital to the QoS of VoIP in IMS network. The optimization of the E-Model provides a tool that is useful for this purpose.
