News16 June 2021Thomas Simoneit

EVS - the codec for better voice quality across all networks

Since the introduction of 4G LTE and VoLTE in 2016, voice quality in mobile networks and on the smartphones people use has kept advancing fast.

Two trends are accelerating adoption of this HD-voice technology: first, the switch-off of 3G networks is pushing users to replace devices faster, since many smartphones that only supported 3G now have to be swapped for new 4G or 5G devices with HD-voice capability. Second, the nearly complete shift to all-IP lines in fixed networks is likewise speeding up device replacement. Here too, modern corded or DECT handsets are taking over, supporting HD voice via the G.722 codec.

Voice quality

Once the EVS codec is in use across carrier networks and user devices, voice quality on fixed and mobile lines becomes fully comparable to OTT calls made through the common messenger apps. Network services such as voicemail or IVR solutions also benefit from HD-voice quality and the EVS codec through an improved user experience. Many users with current smartphones or fixed-line handsets have already grown used to this high voice quality and now take it for granted.

What technical advances does the EVS codec bring?

In terms of voice quality, the EVS codec is the first implementation to handle audio frequencies of up to 20 kHz in full-band mode. As a reminder, the entire audible spectrum for humans runs from roughly 20 Hz to 20 kHz, though it narrows with age.

Besides adapting the audio bandwidth, the EVS codec also uses speech compression to significantly cut the volume of data transmitted across networks. Depending on the bandwidth available in a given IP network, the codec adjusts its compression rate and scales the required transmission bandwidth across a very wide range, from 5.9 Kbit/s up to 128 Kbit/s.

The evolution

Since the introduction of ISDN in the 1980s, the G.711 codec, with an audio bandwidth of up to 3.4 kHz (narrowband), was the reference standard. The AMR-WB (wideband) codec that followed, already used in 3G UMTS networks, marked the next milestone, doubling the audio bandwidth to 7 kHz and delivering markedly better speech intelligibility. The EVS codec now raises the audio bandwidth to 20 kHz, bringing far more detail to phone calls at hi-fi quality.

Benefits of EVS technology for network operators

All solutions built on the CreaLog SDP7 platform fully support the EVS codec along with many other codecs. With full HD-voice technologies, service providers overcome the limitations that have held back their networks so far, such as reduced audio bandwidth and codecs focused purely on speech intelligibility. Through QoS management in 4G/5G networks, EVS lets operators outperform OTT messenger services (WhatsApp, Signal, Telegram, ...) not only on audio quality but also on service robustness and availability. This even gives network operators a chance to win back ground previously lost to OTT services.