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Why Audio MOS testing is more important than ever!

Updated: Mar 31

Include Audio MOS testing to ensure superior QoS and QoE audio quality for your end users.

The beginning of an end for 3G Networks


Many mobile operators have taken the decision to switch off 3G in order to free up frequencies for 4G and 5G and some of them were already targeting to phase out 3G by the end of 2020. With all this talk on 5G and its new capabilities, it is easy to forget that many end users have not actually transitioned to 4G yet.


This move by operators to phase out 3G and in some cases 2G networks will also encourage a move from the end-users towards VoLTE enabled devices to ensure optimum quality of voice calls as the alternative will be circuit switch fallback (CSFB) to 2G which will not provide acceptable voice quality. The consumers are more demanding and when they have to make voice calls, they expect stellar audio quality.


It is not surprising that according to a consumer survey by Deloitte the number one reason in the US why end-users are leaving a mobile network is the voice quality. Voice quality remains an important factor for end-users and many media review companies and Mobile Network Operators are now heavily including it in their testing scope. A European Operator will now include Audio MOS as part of their device acceptance process emphasizing the importance of Audio MOS testing.


VoLTE will be the foundation for 5G Voice Service

Despite the maturity of the IMS framework, there is still lots of room for improvement. According to the data shared by Emanuel Kolta from GSMA intelligence in November 2020 only 30% of the mobile operators that have launched 4G have also deployed commercial VoLTE services. The rollout of 5G is also expected to boost the pace of VoLTE launches over the next five years. As 5G will no longer support circuit-switched fallback (CSFB) for voice, Mobile Network Operators will need to rely on VoLTE in order to provide voice services for their end-users.


SmartViser's unique fully test automated offering for Audio MOS scoring



At SmartViser we have noticed the increased number of requests from our OEMs and MNOs customers alike to include voice quality Audio MOS in the list of KPIs currently supported by viser™. Placing our customers at the heart of innovation our R&D has developed the first version of a fully automated Audio MOS scoring based on POLQA™ industry standard which was launched in 2019 with great feedback. viser™ test automation now includes Audio MOS measurement in the following states:​

  • Audio Uplink

  • Audio Downlink

  • End To End

  • Scalable or Lab, Field testing and large-scale deployments​

The Mean Opinion Score, or MOS as it is now widely known, assesses the quality of voice of calls using a scale of 1-5 (5 being the highest quality) based on the scientific algorithm POLQA ™.A score of 1 means that despite great effort, it is impossible to understand what is being said during the call (the call repeatedly cuts in and out). A score of 5 means the quality is excellent, with no effort required to understand what is being said. The MOS makes it possible to compare a variety of codecs and audio connections.



The Audio Quality can be tested or monitored whatever the technology (2G-3G-4G-5G, VoIP: VoLTE - VoWifi, or mixed …). It offers great opportunities for OEMs/ODMs to fully test their device and ensure it decodes correctly and with the highest quality voice calls in any network infrastructure.​


Truly device agnostic that can be used in any device.




viSer Audio MOS test automation allows Mobile Operators and smartphone manufacturers to test voice quality on any device Android or ios.


Audio MOS can be used for:

  • Voice Calls

  • Skype Calls

  • Viber Calls

  • MS Teams Calls

  • WhatsApp calls

  • Google Meet

  • Other OTT

Do you want to know more?

Contact us for a free trial of viSer Test Automation with Audio MOS?








or message us to arrange a chat








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