HD Voice

User experience is based on expectations – and they are rising. Many people making use of over-the-top (OTT) applications, such as Skype and Facetime, have enjoyed crystal clear speech quality for many years. Commercial voice service providers will have to adapt to the quickly changing expectations and embrace HD voice.


Modern HD voice codecs support numerous different modes and bandwidths. This would be of little importance to VoIP monitoring, if the in-call user experience would not be impacted by the specific codec parameters. The opposite is true. For example, the R-Factor of EVS WB bitrate modes ranges from 99 (7.2k) to 129 (24.4k), which translates to a MOSWB range of 3.91 to 4.5. According to ITU-T G.107 this leaves user satisfaction between “some dissatisfied” to “very satisfied”.


This means the actual user experience strongly depends on the codec and its parameters, which are not all under full control of a VoIP or VoLTE service provider. Quality can change on a packet by packet basis – put to the extreme, user satisfaction can change every 20ms.


Qrystal’s RTP monitoring technology analyzes every RTP packet – including the specific audio encoding – to accurately estimate the user experience for every 5 second timeslice.