Enhanced Voice Services (EVS)

EVS in a nutshell
© Fraunhofer IIS

Full-HD Voice quality for mobile telephony


EVS is especially designed for VoLTE (Voice over LTE) services. It enables phone calls with Full-HD Voice quality, bringing call fidelity up to the same level as today’s other digital media services. Integrating state-of-the-art speech and audio coding technology, EVS removes the limitations of bandlimited and voice-centric codecs that were previously used in mobile communications.

The GSMA has nominated EVS as the mandatory audio codec for superwideband transmissions via VoLTE (please also see "Permanent Reference Dokument IR.92 - IMS Profile for Voice and SMS").

All 5G Voice services benefit from EVS codec support as the codec is mandatory for all configuration of this services. This will also enable future-proof standalone 5G networks (without LTE user plane) through EVS. For more details see also GSMA PRD NG.114 “IMS Profile for Voice, Video and Messaging over 5GS”.




...enables Full-HD Voice audio quality

EVS delivers unprecedented quality for speech, background music and mixed content for narrow-, wide-, superwide- and full-band services, outperforming the audio quality of today’s mobile phone calls and over-the-top communication services.


...delivers high efficiency and versatility

EVS offers a wide range of bit rates from 5.9 kbit/s to 128 kbit/s, allowing service providers to optimize network capacity and call quality as desired for their service. Bit rates for narrow- and wideband start at 5.9 kbit/s, while superwideband Full-HD Voice audio quality is supported from 9.6 kbit/s on. EVS also significantly improves the audio quality over legacy codecs at popular mobile bit rates such as 13.2 kbit/s and 24 kbit/s.


...ensures a reliable service

Mobile network services such as VoLTE or Voice over WiFi can be affected by packet loss issues, resulting in a negative impact on speech intelligibility. EVS utilizes unique concealment techniques to minimize the impact of packet loss caused by adverse conditions in the transmission channel.


...is backward-compatible to existing VoLTE services

The codec’s integrated AMR-WB interoperability mode eliminates the need for a separate AMR-WB implementation allowing the signal to quickly switch between VoLTE (4G) and circuit switched networks (3G) when network conditions warrant a transition.


There are several operators worldwide which have already launched EVS powered VoLTE services. These include:

  • NTT DoCoMo
  • T-Mobile USA
  • T-Mobile Poland
  • Vodafone Germany
  • Vodafone Romania
  • Orange Romania
  • Orange France
  • Korean operators (SK Telecom, KT, LG Uplus)
  • Deutsche Telekom
  • KDDI Japan
  • China Mobile
  • EE United Kingdom
  • Vodafone Netherlands
  • KPN Netherlands
  • Airtel India
  • A1 Telekom Austria
  • Swisscom
  • Verizon
  • Turkcell
  • TIM
  • Wind Tre
  • Vodafone Idea
  • Magyar Telekom

The number of smartphones supporting EVS is growing steadily. Currently there are more than 200 models from different manufacturers.

Patent licensing

Information about EVS patent license is available here.