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 "Official Document IR.92 - IMS Profile for Voice and SMS").




...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
  • Korean operators (SK Telecom, KT, LGUplus)
  • Deutsche Telekom
  • KDDI Japan
  • China Mobile
  • EE United Kingdom
  • Vodafone Netherlands
  • Airtel India
  • A1 Austria
  • Swisscom
  • Verizon

The number of smartphones supporting EVS is growing steadily. Currently there are about 200 models from different manufacturers, such as:

  • Apple
  • Samsung
  • Google
  • HTC
  • Huawei
  • LG
  • Motorola
  • Nokia
  • Panasonic
  • Sony
  • Xiaomi
  • and many more