the application would transmit a constant data stream regardless of whether the speaker was talking or in silence. It was also observed that some of these clients either had the VAD as an optional feature or included non-standard implementations which did not transmit comfort silence frames with sufficient frequency, which in standard VoLTE should be sent every 160 ms. Native VoLTE client scored 3.9 with AMR WB 23.85 kbps codec on the same scale, using both VAD and standardized implementation of comfort silence frames. The OTT VoIP applications scored between 4.1 and 4.2 in the POLQA SWB scale using proprietary codecs, quite close to native VoLTE client. The future VoLTE voice quality can be further improved with the new super wideband (SWB) and fullband (FB) codecs, which will be able to cover the whole voice and audio bandwidths. 3GPP has defined a SWB/FB codec in Release 12 called Smartphone Optimization 3G CS VoLTE Figure 16.26 Mouth to ear delay Enhanced Voice Services (EVS) codec. That codec will make it possible for VoLTE to match and beat the voice quality of all OTT clients. In terms of mouth to ear delay in Figure 16.26, VoLTE client provided the lowest value of 164 ms, well below the target of 200 ms for excellent quality. This was even significantly lower than 3G CS call which resulted only slightly under the 300 ms target. The OTT VoIP applications generated higher latency, with two of them exceeding the 300 ms target. However, it is important to note that in these tests the routing of the VoIP streams was done directly between the two calling parties' IP addresses, while in some other implementations a gateway may be used to route the packets adding additional delays to the voice transfer. Additionally, in a live network transport delays may increase the overall delay further, depending on the network architecture. Figure 16.27 presents the average user throughput and Figure 16.28 the current consumption over a 2-minute call. In this case native VoLTE provided an average of 10.2 kbps, considering th