What are codecs? Audio codec meaning explained
A codec (short for coder-decoder) is a piece of hardware or software that compresses and decompresses digital data so it can travel faster. If you are wondering what codecs are and why they matter, they are the technology that makes modern VoIP and PBX calls possible over the internet. Understanding the basic codec meaning helps a lot when you set up a phone system. The codec for audio you choose has a direct effect on your call quality, delay and bandwidth use.
Why your calls sound the way they do
Picture this. A customer calls your office. Halfway through the conversation their voice starts to sound robotic, or there is a short delay that makes you talk over each other. Most people blame the internet connection. Sometimes that is right. But very often, the way your voice is packed and unpacked plays a big part too.
Every time you make a call over the internet, your voice has to be turned into data, sent across the network and turned back into sound at the other end. A codec does that job, in both directions, many times per second. So it is worth knowing how this works and which option fits your business.
Codec meaning: what it actually does
The codec meaning is in the name: coder and decoder. Here is what happens during a call:
- Coding. Your phone or app picks up your voice through the microphone. It turns that sound into digital data and usually compresses it, so it takes up less space.
- Sending. The data travels over the internet in small packets, often via a SIP trunk.
- Decoding. At the other end, the data is unpacked and turned back into sound your caller can hear.
Both sides of the call need to speak the same language. When a call starts, the devices quickly agree on which format to use. If they cannot find a match, the phone system has to convert between the two formats. This is called transcoding. It works, but it can add a little delay and reduce quality.
What are codecs measured on?
When you compare them, you mostly look at three things:
- Sound quality. How natural and clear a voice sounds. Some only carry the frequencies of a traditional phone line. Others carry a wider range, which people often call HD voice.
- Bandwidth. How much data each call uses. This matters when many colleagues call at the same time over one connection.
- Latency. How much delay is added while the sound is compressed and unpacked. A small delay is fine. A big one makes conversations feel clumsy.
There is always a trade-off. One that saves a lot of bandwidth often gives up a bit of quality. One with top sound quality usually needs more bandwidth.
Popular codecs for audio
You do not need to know them all. These are the ones you are most likely to come across in business telephony.
G.711
G.711 is the classic. It barely compresses the sound, so the quality is the same as a traditional phone line. It uses about 64 kbps per call, plus some network overhead. Because almost every phone and provider supports it, G.711 is a safe default when you have enough bandwidth. In the UK and Europe you will mostly see the A-law version.
G.729
G.729 squeezes your voice down to around 8 kbps. That makes it a popular codec for audio when bandwidth is limited, for example at a small branch office or a location with a weak connection. The sound quality is a little lower than G.711, but for most everyday calls people hardly notice.
G.722
G.722 is a wideband option. It carries a wider range of sound than G.711, so voices sound fuller and more natural. This is what people usually mean by HD voice. It uses about the same bandwidth as G.711, so it is a good choice when your phones and network support it.
Opus
Opus is modern and flexible. It changes its quality and bandwidth on the fly, depending on how good the connection is. That makes it a strong fit for softphones and mobile apps, where the network can change from minute to minute. You find Opus in many browser based and app-based calling tools.
Which codec should your business use?
So, what codecs make sense for you? It depends on your situation.
- An office with a solid fibre connection. G.711 or G.722 gives you clear calls without fuss.
- A busy contact centre with lots of calls at once. Check how much bandwidth all those calls use together. Sometimes a compressed option helps you stay within limits.
- Colleagues who call from home or on the road. Opus copes better with an unstable connection.
- A mix of desk phones, apps and a SIP trunk. Try to use the same settings across the chain, so the system does not have to transcode.
The format you choose is only one part of good call quality. Your internet connection, your network settings and your hardware matter too. That is why it helps to use certified hardware that has been tested to work with your phone system.
How Xelion helps
With Xelion, you do not have to figure all of this out on your own. Xelion is a cloud phone system that runs your telephony on your desk phone, computer and smartphone. Our accredited partners set up your phones, apps and SIP trunk so they work well together, including the codec settings.
A customer calls. You see who it is, pick up and have a clear conversation. Your colleague at home takes the next call in the app, with the same business number. And if you want to check how your lines perform, reportsshow you how many calls came in and how they were handled.
Want to know more about how internet calling works? Read our article on VoIP PBX systems, or see how call management helps you route every call to the right person.
