Updated October 2026: G.711 vs G.722 short answer with RTP payload types and on-the-wire bandwidth; new section on IVAS, the 3GPP Release 18 successor to EVS, and its 2026 deployment status.
Why this matters
If you build video conferencing, telemedicine, contact-center, or any product that can dial a real phone number, your modern audio engine — usually Opus over WebRTC — has to hand the call off to a much older world at the gateway, and that hand-off forces a transcode into one of these speech codecs. This article is for a product manager, founder, or operations lead with no audio background: by the end you will understand what a speech codec is, why these four still dominate telephony in 2026, how their sound quality and bitrate compare, and where each one quietly sets a quality ceiling on calls your users make. Every number here traces back to its controlling standard — the ITU-T Recommendations and 3GPP technical specifications that define each codec — not a secondhand summary.
G.711 vs G.722: the short answer
G.722 sounds clearly better than G.711 and costs the same bandwidth. Both run at 64 kbit/s, but G.711 samples at 8 kHz and carries only the 300–3,400 Hz telephone band, while G.722 samples at 16 kHz and carries 50–7,000 Hz wideband "HD voice" (ITU-T G.711; ITU-T G.722). Use G.722 whenever every hop on the call supports it, and keep G.711 as the fallback, because G.711 is the codec every SIP device and every WebRTC browser must implement (IETF RFC 7874, 2016).
| G.711 (PCMU / PCMA) | G.722 | |
|---|---|---|
| Audio band | 300–3,400 Hz (narrowband) | 50–7,000 Hz (wideband) |
| Sample rate | 8 kHz | 16 kHz |
| Codec bitrate | 64 kbit/s | 64 kbit/s (also 56 / 48 kbit/s modes) |
| IP bandwidth, 20 ms packets | 80 kbit/s | 80 kbit/s |
| RTP payload type (RFC 3551) | 0 (μ-law) / 8 (A-law) | 9 |
| RTP clock rate in SDP | 8,000 Hz | 8,000 Hz (a legacy quirk; real sampling is 16 kHz) |
| WebRTC | Mandatory to implement | Supported in Chrome, Firefox and Safari, not mandatory |
| Typical home | PSTN, SIP trunks, universal fallback | SIP desk phones, conference bridges |
Table 1. G.711 vs G.722 at a glance. The IP bandwidth row is our arithmetic: a 20 ms packet holds 160 bytes of audio plus 40 bytes of RTP, UDP and IPv4 headers, so 200 bytes × 50 packets per second = 80 kbit/s for either codec. Sources: ITU-T G.711, G.722; IETF RFC 3551 (2003), RFC 7874 (2016); MDN WebRTC codecs (checked October 2026).
If you only need the newest name: the latest 3GPP voice codec is IVAS (Immersive Voice and Audio Services), approved in 3GPP Release 18 in June 2024 as the successor to EVS. It is covered below.
What a "speech codec" is, and why it differs from a music codec
A codec is an agreed method for compressing sound on one end of a link and reconstructing it on the other. A speech codec is a codec built for one specific signal: the human voice. That narrow target is what makes it different from a general-purpose music codec like AAC or Opus, and the difference is worth understanding before the four codecs make sense.
A music codec has to handle anything — a cymbal crash, a bass drop, a full orchestra — so it keeps a wide range of frequencies and spends a lot of bits doing it. A speech codec assumes the input is a voice, and a voice is a far simpler, more predictable signal: it sits mostly between 300 and 3,400 hertz (the range an old telephone carried), and it is produced by a physical system — vocal cords, throat, mouth — that can be modelled mathematically.
That model is the key trick. Most modern speech codecs use a method called linear predictive coding, often in a refined form named ACELP — Algebraic Code-Excited Linear Prediction. Instead of storing the sound wave itself, the codec builds a tiny mathematical model of the speaker's vocal tract for each short slice of audio and sends only the model's settings plus a thin "excitation" signal to drive it. The receiver runs the same model in reverse and reconstructs a voice that sounds close to the original. Because a voice model needs far less data than a raw wave, ACELP codecs carry intelligible speech at remarkably low bitrates — figures like 4.75 kbit/s that no music codec could approach.
This is why speech codecs and music codecs are separate worlds, explained more fully in how audio compression works. A speech codec trades away the ability to carry music for the ability to carry a voice cheaply and robustly. The four codecs below are the ones a video product will still meet, in roughly the order they arrived.
Figure 1. Four decades of speech coding: each codec pushed audio bandwidth higher while bitrate trended lower. EVS is the first to reach fullband 20 kHz quality on a phone call.
G.711: the codec under almost every phone call
G.711 is the oldest and simplest of the four, and the one you are most certain to meet. The ITU-T — the standards arm of the International Telecommunication Union, the body that governs global telephony — approved G.711 in 1972; the edition in force today dates from November 1988, and it has been the bedrock of digital telephone networks ever since (ITU-T G.711).
G.711 does almost no compression. It takes a voice, limits it to the classic telephone band of 300–3,400 Hz, measures it 8,000 times per second — a sample rate of 8 kHz — and stores each measurement in 8 bits, for a constant 64 kbit/s (ITU-T G.711). The sample rate is how many times per second the system measures the sound, explained in sample rate. Run the arithmetic out loud:
8,000 samples per second × 8 bits per sample = 64,000 bits per second
64,000 bits per second ÷ 1,000 = 64 kbit/s
The "compression" in G.711 is one clever step called companding — compressing the loud parts and expanding them back on the other side, so 8 bits sound like more. There are two flavours: μ-law (mu-law), used in North America and Japan, which encodes 14-bit linear samples into 8 bits; and A-law, used through most of the rest of the world, which encodes 13-bit samples (ITU-T G.711). The two are not interoperable on the wire, which is why a transatlantic call needs a conversion at the boundary — a small but real pitfall.
Because G.711 is everywhere, it is the codec that two systems fall back to when they cannot agree on anything fancier. In a Session Initiation Protocol call — SIP, the signalling that sets up most VoIP — G.711 carries the fixed RTP payload types 0 for μ-law (PCMU) and 8 for A-law (PCMA), two of the handful of audio codecs with permanently reserved numbers (IETF RFC 3551). WebRTC made G.711 mandatory in every browser alongside Opus (IETF RFC 7874, 2016), which is why a browser call and a phone gateway can always agree on something. RTP is the real-time transport protocol that actually carries the audio packets, covered in RTP timestamps and sender reports. For a product team, the lesson is blunt: if your gateway offers nothing else, the call will run on G.711 — full 64 kbit/s, telephone-narrow sound, universally understood.
G.722: the first "HD voice"
Sixteen years later, the ITU-T widened the sound. G.722, approved in November 1988, was the first standard to carry wideband speech — a frequency range of roughly 50–7,000 Hz, double the bandwidth of G.711 (ITU-T G.722). That extra high-frequency range is what makes a voice sound natural rather than "telephone-thin", and it is the reason G.722 became the original HD Voice codec.
G.722 samples the voice at 16 kHz (not 8) and uses a technique called sub-band ADPCM: it splits the signal into a lower and an upper frequency band, then encodes each band with adaptive differential coding — storing the change between samples rather than the samples themselves (ITU-T G.722). It runs in three modes that all fit inside a 64 kbit/s channel: 64, 56, or 48 kbit/s for the audio, with the spare 8 or 16 kbit/s available for a side data channel (ITU-T G.722).
Where do you still meet G.722? It is the default wideband codec on most desk-phone (SIP) systems and many enterprise conferencing bridges, because it delivers a clear quality jump over G.711 for almost no extra complexity and no extra bandwidth — it fits in the same 64 kbit/s slot. If your product connects to a corporate phone system or a hardware conference room, the wideband leg of that call is very often G.722.
One G.722 detail breaks real integrations. Its static RTP payload type is 9, and its SDP line says G722/8000 even though the codec samples at 16 kHz: the 8,000 Hz RTP clock rate "was erroneously assigned in RFC 1890 and must remain unchanged for backward compatibility" (IETF RFC 3551). A gateway or recorder that "fixes" the clock to 16,000 Hz produces timestamps that run at double speed, which shows up as broken jitter statistics and drifting lip sync. For the one-line definition, see the G.722 glossary entry.
Opus vs G.722. Opus wins whenever both ends speak it: IETF guidance puts good wideband speech at 16–20 kbit/s with Opus (IETF RFC 7587, 2015), about a quarter of G.722's 64 kbit/s, with better packet-loss handling. G.722 wins on reach, because desk phones, SIP trunks and conference-room hardware support it, while many of them do not support Opus. In practice your app runs Opus to the gateway and G.722 from the gateway to the desk phone.
Common mistake: assuming "wideband" always means "better on this call"
A frequent planning error is to treat a wideband codec as automatically better for every call. It is not, for two reasons. First, both ends and every box in between must support wideband; a single narrowband gateway in the path drags the whole call back to 3.4 kHz, and the wideband codec gains you nothing. Second, wideband only helps if the audio was captured wide in the first place — upsampling a narrowband recording into G.722 adds no real detail. The practical rule: negotiate the best codec the whole path supports, but design your quality expectations around the weakest link in the chain, not the codec name in your own config.
AMR and AMR-WB: the codecs built for bad radio
The phone network is one thing; a mobile network is harder. Radio fades, hands move, signal drops — and a codec for cellular voice has to survive all of it. That is the job AMR was built for.
AMR — Adaptive Multi-Rate — is the speech codec of 2G and 3G mobile networks, specified by the 3GPP (the body that standardizes mobile networks) in 3GPP TS 26.071. Its defining feature is in the name: it is adaptive, meaning it can change its bitrate on the fly, every 20 milliseconds, to match how good the radio link is at that instant (3GPP TS 26.071). When the signal is strong it spends more bits for better sound; when the signal weakens it drops to a lower bitrate so the call survives instead of breaking up.
AMR is narrowband (8 kHz sampling, the same 3.4 kHz voice band as G.711) and offers eight bitrate modes: 4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, and 12.2 kbit/s (3GPP TS 26.071). It uses the ACELP voice-model coding described earlier, which is how it fits an intelligible call into as little as 4.75 kbit/s — roughly one-thirteenth of G.711's data.
AMR-WB is the wideband upgrade, and it carries a second name worth knowing: the ITU-T adopted the identical codec as G.722.2, so "AMR-WB" and "G.722.2" are the same thing (3GPP TS 26.190; ITU-T G.722.2). Developed by Nokia and VoiceAge, AMR-WB widens the sound back to 50–7,000 Hz like G.722 but does it far more efficiently, with nine modes from 6.60 to 23.85 kbit/s (3GPP TS 26.190). AMR-WB is the codec behind most "HD Voice" branding on 3G and 4G mobile calls. For a product team bridging into mobile, AMR-WB is the codec your wideband mobile leg most likely runs on before the move to VoLTE.
Narrowband AMR is shrinking with the networks it was built for. As of August 2026, the GSA counts 174 operators in 67 markets that have started switching off 3G, and 102 of them have finished (GSA 2G/3G Switch-Off report, August 2026). Once a market's 3G is gone, mobile voice runs on VoLTE or VoNR, where AMR-WB and EVS do the work.
Figure 2. AMR and AMR-WB scale their bitrate to match the radio link. The codec steps up or down between these modes every 20 ms — more bits when the signal is good, fewer when it fades.
EVS: the modern VoLTE codec that finally caught up to music
The newest of the four is the one inside modern mobile calls. EVS — Enhanced Voice Services — was standardized by 3GPP in 2014 (3GPP TS 26.441) as the voice codec for VoLTE (Voice over LTE) and now VoNR (Voice over New Radio, on 5G). It is the codec your phone uses for an "HD+" call on a modern network.
EVS does three things its predecessors could not, all at once. First, it spans every bandwidth in one codec: narrowband, wideband, super-wideband (up to 14 kHz), and fullband (up to 20 kHz) — and 20 kHz is the full range of human hearing, the same as a music track (3GPP TS 26.441). A voice call on EVS can sound like the person is in the room, not on a phone. Second, it covers a wide bitrate range — its super-wideband modes alone run 9.6, 13.2, 16.4, 24.4, 32, 48, 64, 96, and 128 kbit/s — and at the low end it matches or beats AMR-WB's quality at the same rate (3GPP TS 26.441; Nokia). Third, it is built to survive packet loss with a channel-aware mode and strong packet-loss concealment, the techniques that hide missing audio when the network drops data, covered in packet loss concealment.
One detail makes EVS painless to deploy: it includes an AMR-WB interoperable mode, so an EVS phone can talk to an AMR-WB phone without a quality-wrecking transcode (3GPP TS 26.441). That backward compatibility is why carriers could roll EVS out gradually. For a product bridging into a 2026 mobile network, EVS is the best-sounding leg you can hope to reach — and the reason a modern mobile call can sound dramatically better than the same call a decade ago.
What's the latest 3GPP voice codec? IVAS
The latest 3GPP voice codec is IVAS, Immersive Voice and Audio Services, approved in 3GPP Release 18 in June 2024 (Nokia). IVAS is an extension of EVS rather than a clean break: it is backward compatible with EVS (3GPP), so an IVAS phone can still hold a normal EVS call. What it adds is space. Besides mono voice it codes stereo, binaural audio, multichannel layouts up to 7.1+4, Ambisonics up to third order, audio objects and MASA, a parametric format designed for a phone's own microphones (3GPP).
Bitrates follow the content: mono from 5.9 to 128 kbit/s like EVS, stereo and binaural from 13.2 to 256 kbit/s, and immersive formats from 13.2 up to 512 kbit/s, specified in the 3GPP TS 26.250 series (VOCAL Technologies summary of TS 26.250–26.258).
Where it stands in October 2026:
- June 2024: Nokia placed the first IVAS call over a public 5G network (Nokia, 10 June 2024).
- December 2025: Fraunhofer IIS and Nokia completed the first interoperable IVAS call between two different client implementations over Nokia's 5G IMS network (Fraunhofer IIS, 16 December 2025).
- March 2026: public interoperability demos at MWC Barcelona; Nokia describes the industry as moving toward "deployment readiness", without naming an operator launch (Nokia, 24 February 2026).
- May 2026: Via LA added licensors to its voice codec patent pool, which covers EVS and IVAS (Via LA, 20 May 2026).
For a product team this means: plan bridges for G.711, G.722, AMR-WB and EVS today. We found no commercial operator launch of IVAS calling as of October 2026, so treat it as the codec to watch for 5G-Advanced, not one your gateway has to speak this year.
The four compared, plus the successor
| Codec | Year | Standard | Bandwidth | Sample rate | Bitrate(s) | Where you meet it |
|---|---|---|---|---|---|---|
| G.711 | 1972 | ITU-T G.711 | Narrowband (3.4 kHz) | 8 kHz | 64 kbit/s (fixed) | VoIP / SIP fallback, PSTN |
| G.722 | 1988 | ITU-T G.722 | Wideband (7 kHz) | 16 kHz | 48 / 56 / 64 kbit/s | Desk phones, conf. bridges |
| AMR | 1999 | 3GPP TS 26.071 | Narrowband (3.4 kHz) | 8 kHz | 4.75–12.2 kbit/s (8 modes) | 2G / 3G mobile voice |
| AMR-WB (G.722.2) | 2001 | 3GPP TS 26.190 | Wideband (7 kHz) | 16 kHz | 6.60–23.85 kbit/s (9 modes) | 3G / 4G HD Voice |
| EVS | 2014 | 3GPP TS 26.441 | NB → Fullband (20 kHz) | 8–48 kHz | 5.9–128 kbit/s | VoLTE / VoNR, modern mobile |
| IVAS (successor) | 2024 | 3GPP TS 26.250 series | NB → Fullband + stereo / immersive | 8–48 kHz | 5.9–512 kbit/s | 5G-Advanced trials, no commercial launch yet |
Table 2. The four speech-codec families a video product still meets in 2026, plus IVAS. G.711 is the universal floor; G.722 the wideband desk-phone default; AMR / AMR-WB the cellular legacy; EVS the modern VoLTE codec; IVAS its immersive successor. Sources: ITU-T G.711, G.722, G.722.2; 3GPP TS 26.071, TS 26.190, TS 26.441; IVAS bitrates per the TS 26.250 series (VOCAL Technologies summary).
Why this still matters when your product runs Opus
Your product almost certainly does not encode voice in any of these codecs natively. A modern real-time stack uses Opus over WebRTC, covered in Opus, the open codec that ate WebRTC, because Opus is better than all four at the same bitrate. So why care?
Because the moment your call leaves the internet and touches the phone network — a dial-out to a mobile, a customer joining by phone, a bridge into a legacy PBX — a gateway transcodes Opus into whichever speech codec that network speaks. Transcoding means decoding the audio fully and re-encoding it in the other codec, and every transcode costs a little quality and adds a little delay. The codec on the far side becomes the ceiling: if the call lands on G.711, no amount of Opus quality on your side makes it sound better than narrowband telephone. Knowing which codec each path uses tells you exactly where your audio quality is being capped, and whether a wideband-capable gateway (G.722, AMR-WB, EVS) is worth pursuing for a given route.
The same ceiling applies to AI voice agents. A customer who phones an AI agent often arrives over a SIP trunk or a telephony API as G.711 at 8 kHz, so the speech recognizer hears telephone-band audio no matter how good the model is. Opus itself keeps moving: libopus 1.6 (December 2025) added a bandwidth-extension module that rebuilds fullband from wideband audio and improved its deep-learning redundancy (Xiph.Org, 15 December 2025), widening the gap between what your app can carry and what the phone leg delivers.
FAQ
Is G.722 better than G.711?
Yes, for voice quality: G.722 carries 50–7,000 Hz against G.711's 300–3,400 Hz at the same 64 kbit/s. G.711 is only "better" for compatibility, since every SIP device and every WebRTC browser must support it.
Does G.722 use more bandwidth than G.711?
No. Both use 64 kbit/s of audio and about 80 kbit/s on an IP network with 20 ms packets, so switching a trunk from G.711 to G.722 costs no extra capacity.
Why does SDP say G722/8000 if G.722 samples at 16 kHz?
The 8,000 Hz RTP clock rate was assigned by mistake in RFC 1890 and kept for backward compatibility (IETF RFC 3551). Leave it at 8000 in SDP and RTP timestamps.
Should I use Opus or G.722?
Use Opus between your own apps and servers; it reaches good wideband speech at 16–20 kbit/s (IETF RFC 7587). Use G.722 on the leg to SIP desk phones and conference hardware that do not support Opus.
What is the EVS codec?
EVS (Enhanced Voice Services) is the 3GPP voice codec for VoLTE and VoNR, standardized in 2014 in TS 26.441. It runs from narrowband to fullband 20 kHz at 5.9–128 kbit/s and can interoperate with AMR-WB.
What is the AMR codec?
AMR (Adaptive Multi-Rate) is the 3GPP narrowband speech codec of 2G and 3G networks. It switches between eight bitrates from 4.75 to 12.2 kbit/s every 20 ms to survive a weak radio link (3GPP TS 26.071).
What is the latest 3GPP voice codec?
IVAS (Immersive Voice and Audio Services), approved in 3GPP Release 18 in June 2024. It extends EVS with stereo and spatial audio up to 512 kbit/s; as of October 2026 it is in interoperability trials, not commercial service.
Which speech codec do AI phone agents receive?
Often G.711 at 8 kHz, because that is the codec every SIP trunk and phone gateway can fall back to. Speech recognition then works on telephone-band audio, so test your ASR on 8 kHz input rather than on clean 48 kHz recordings.
Free download: Speech codecs cheat sheetOne page: G.711 vs G.722 vs AMR vs EVS, the bitrate-and-bandwidth numbers, where each codec shows up, and the transcoding-ceiling pitfall when bridging into the phone network.Where Fora Soft fits in
We build video conferencing, telemedicine, e-learning, contact-center, and OTT products, and the phone-network bridge shows up in most of them — a patient who joins a telemedicine consult by ordinary phone, a participant dialing into a conference, a contact-center agent on a SIP trunk. The practical engineering is in the hand-off: choosing gateways that negotiate the widest codec a route supports, minimizing the number of transcodes between Opus and the speech codec, measuring the real mouth-to-ear quality that survives the gateway, and keeping a clean G.711 fallback so a call never fails for lack of a shared codec. We have made those telephony-interop trade-offs across conferencing and telemedicine builds since 2005. Our video conferencing development team builds the dial-in bridge into the product, and our Telnyx SIP and voice integration developers connect it to the phone network with the widest codec each route supports. When the caller is talking to software rather than a person, our AI call agent development team builds agents that answer on SIP trunks and are tested on real 8 kHz telephone audio, not studio recordings.
The book
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
The four codecs on this page get a chapter of their own in this volume, next to Opus and the AAC family, so you can read what your own side encodes and what the gateway turns it into side by side. It builds that on the sampling, bit-depth and channel-layout material you need the moment an 8 kHz phone leg meets a 48 kHz conference, then carries on into loudness, accessibility and the real-time voice processing that runs before the encoder. Written by Nikolay Sapunov, CEO at Fora Soft.
Do you know where the codec ceiling sits on your calls?
Tell us which routes your calls take into the phone network and we will map where the quality is actually capped, how many transcodes sit in each path, and what a wideband-capable gateway would buy you. 250+ video products shipped since 2005.
See our case studies
Case study
TransLinguist
Interpreting for the NHS national framework in 75+ languages with captions in 22 — the interpreter hears whatever the weakest leg allows, so the codec a route negotiates decides how much of a consonant survives.
Case study
VocalViews
Speech recognition in 30+ languages across 800K+ verified panelists and 5K+ studies — every transcode before the recognizer costs accuracy, so we count the hops between capture and ASR.
Case study
WorldCast Live
Five channels of audio inside 1.5 Gb/s at 0.4–0.5 s latency for 10,000 viewers — what the same voice is worth on a path that never touches the phone network.
What to read next
Codecs
Opus: The Open Codec That Ate WebRTC
The codec your own side almost certainly runs, and the one every gateway transcodes away from.
Codecs
How Audio Compression Works
The four ideas under ACELP, and why a voice model needs so many fewer bits than a waveform.
Real-time voice
Packet Loss Concealment (PLC)
What the channel-aware mode of EVS is actually hiding, and how the receiver fills the gap.
Decision guide
How to Choose an Audio Codec in 2026
A decision tree that starts from where your audio has to land, not from what your stack prefers.
References
- ITU-T Recommendation G.711, Pulse code modulation (PCM) of voice frequencies (edition in force 11/1988; codec originally approved 1972). The controlling specification for G.711: 8 kHz sampling, 8-bit samples, 64 kbit/s, the 300–3,400 Hz telephone band, and the μ-law / A-law companding laws (μ-law from 14-bit linear, A-law from 13-bit). Read from the ITU-T publication page. https://www.itu.int/rec/T-REC-G.711/
- ITU-T Recommendation G.722, 7 kHz audio-coding within 64 kbit/s (current edition 09/2012; originally approved November 1988). The controlling specification for G.722: 16 kHz sampling, 14-bit uniform PCM input, sub-band ADPCM, the 50–7,000 Hz wideband range, and the 64 / 56 / 48 kbit/s operating modes with auxiliary data channel. Read from the ITU-T summary page. https://www.itu.int/dms_pubrec/itu-t/rec/g/T-REC-G.722-201209-I!!SUM-HTM-E.htm
- 3GPP TS 26.071, Mandatory speech CODEC speech processing functions; AMR speech CODEC; General description. The controlling specification for narrowband AMR: eight source rates from 4.75 to 12.2 kbit/s, 8 kHz sampling, 20 ms frames, MR-ACELP coding, and bitrate switching every 20 ms. https://www.3gpp.org/dynareport/26071.htm
- 3GPP TS 26.190, Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; Transcoding functions. The controlling specification for AMR-WB: nine modes from 6.60 to 23.85 kbit/s, 16 kHz sampling, 50–7,000 Hz wideband, ACELP. https://www.3gpp.org/dynareport/26190.htm
- ITU-T Recommendation G.722.2, Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB) (2003). Confirms that ITU-T G.722.2 and 3GPP AMR-WB are the identical codec; cited to establish the dual naming. Where the 3GPP and ITU-T texts describe the same codec, the 3GPP TS is treated as the primary owner for mobile context. https://www.itu.int/rec/T-REC-G.722.2/
- 3GPP TS 26.441, Codec for Enhanced Voice Services (EVS); General overview. The controlling specification for EVS: narrowband / wideband / super-wideband (14 kHz) / fullband (20 kHz) operation, the super-wideband bitrate set (9.6–128 kbit/s), channel-aware mode, and the AMR-WB interoperable mode. https://www.3gpp.org/dynareport/26441.htm
- IETF RFC 3551, RTP Profile for Audio and Video Conferences with Minimal Control (H. Schulzrinne, S. Casner, July 2003). Source for the statically assigned RTP payload types: PT 0 = PCMU (G.711 μ-law), PT 8 = PCMA (G.711 A-law); also the static type for G.722. Used for the SIP / RTP fallback discussion. https://www.rfc-editor.org/rfc/rfc3551.html
- Nokia, The 3GPP Enhanced Voice Services (EVS) codec (white paper). First-party deployer source for EVS quality positioning: at low bitrates EVS matches or beats AMR-WB; at higher bitrates it delivers near-transparent fullband audio; channel-aware coding and improved packet-loss concealment. Used only for quality framing; all numeric codec facts come from 3GPP TS 26.441, which overrides any vendor figure where they differ. https://www.nokia.com/
- 3GPP, EVS Codec — Enhanced Voice Services Codec for LTE (3GPP news / project page). Background on why EVS was developed for VoLTE, its mandatory status for super-wideband VoLTE, and the rollout context. Deployment framing only; numeric facts from TS 26.441. https://www.3gpp.org/news-events/3gpp-news/evs-news
- IETF RFC 4867, RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs (J. Sjoberg et al., April 2007). Source for how AMR and AMR-WB are packetized over RTP, used to support the gateway / transport discussion; the codec definitions themselves come from 3GPP TS 26.071 and TS 26.190. https://www.rfc-editor.org/rfc/rfc4867.html
- IETF RFC 7874, WebRTC Audio Codec and Processing Requirements (May 2016). Makes Opus and G.711 (PCMU / PCMA) mandatory to implement in WebRTC endpoints. https://datatracker.ietf.org/doc/rfc7874
- IETF RFC 7587, RTP Payload Format for the Opus Speech and Audio Codec (June 2015). Section 3.1.1 gives the Opus bitrate sweet spots, including 16–20 kbit/s for wideband speech. https://www.rfc-editor.org/rfc/rfc7587.html
- MDN Web Docs, Codecs used by WebRTC (checked October 2026). Browser support table: G.722 supported in Chrome, Firefox and Safari; Opus and G.711 mandatory. https://developer.mozilla.org/en-US/docs/Web/Media/Guides/Formats/WebRTC_codecs
- 3GPP, IVAS technology highlights. IVAS as the EVS extension for Release 18: backward compatibility with EVS; stereo, multichannel up to 7.1+4, binaural, Ambisonics up to third order, objects and MASA. https://www.3gpp.org/technologies/ivas-highlights
- Nokia, Immersive voice: quick guide. States that 3GPP approved IVAS in its Release 18 specification in June 2024, developed by 13 companies. https://www.nokia.com/licensing/audio/future-of-voice-calling/quick-guide/
- VOCAL Technologies, Immersive Voice and Audio Services (IVAS) Codec. Summary of the 3GPP TS 26.250–26.258 series used for the IVAS bitrate ranges (mono 5.9–128, stereo 13.2–256, immersive 13.2–512 kbit/s). https://vocal.com/speech-coders/ivas/
- Nokia newsroom, Nokia makes world's first immersive voice and audio call (10 June 2024). First IVAS call over a public 5G network; the technology had not yet been implemented in mobile networks. https://www.nokia.com/newsroom/nokia-makes-worlds-first-immersive-voice-and-audio-call/
- Fraunhofer IIS, First Interoperable Immersive Voice and Audio Services Call over 5G IMS (16 December 2025). https://www.audioblog.iis.fraunhofer.com/ivas-call
- Nokia, The future of immersive audio at MWC 2026 (24 February 2026). IVAS interoperability demos; industry moving toward deployment readiness. https://www.nokia.com/blog/the-future-of-immersive-audio-at-mwc26/
- Via Licensing Alliance, Voice codec program press release (20 May 2026). Patent pool covering EVS and IVAS. https://www.via-la.com/wp-content/uploads/2026/05/Via-Voice-Codec-PR_final.pdf
- GSA 2G/3G Switch-Off report, as reported by Advanced Television, Data: Europe leads 3G switch-off (12 August 2026). 174 operators in 67 markets have started 3G switch-off, 102 completed. https://www.advanced-television.com/2026/08/12/data-europe-leads-3g-switch-off/
- Xiph.Org, libopus 1.6 release notes (15 December 2025). Bandwidth extension to fullband, 96 kHz Opus HD, improved Deep Redundancy (DRED). https://opus-codec.org/release/stable/2025/12/15/libopus-1_6.html
