Popular codecs used in VoIP applications and devices
If you make calls over the Internet using Voice over IP (VoIP) or other digital networks, you must encode the voice to digital data and vice versa. In the same way, the data is compressed so that it is transmitted faster and the calling experience is better. This encoding is achieved by codecs (short for encoder decoder).
There are many codecs for audio, video, fax, and text .
Below is a list of the most common codecs for VoIP. As a user, you may think you have little to do with them, but it’s always good to know a minimum about them, because you need to decide that your company will one day have codecs associated with VoIP; or at least a few days may say a few words on Greek VoIP.
One specific scenario where you might be asked to understand codecs is when you need to consider software or hardware before purchasing. For example, you can decide whether to install this calling application or one based on the codecs available for your calls, depending on your needs. Some phones also have codecs turned on that you might want to consider before investing.
Common VoIP codecs
|Codec||Bandwidth / kbps||comments|
|G.711||64||Provides accurate call forwarding. Very low CPU requirements. Two directions require at least 128 kbps. It is one of the oldest codecs around (1972) and works best with high bandwidth, making it weekly for the Internet for a while, but still for LANs. It gives a MOS of 4.2, which is quite high, but must be met in optimal conditions.|
|G.722||48/56/64||Adaptation with different compressions and bandwidth are network congestion. This hits the frequency range twice as large as G.711, resulting in better quality and clarity, close to or even better than with PSTN.|
|G.723.1||5.3 / 6.3||High compression with high quality sound. Can be used with dial-up and low-bandwidth environments as it works at very low bit rates. However, this requires more CPU power.|
|G.726||16/24/32/40||Advanced version of G.721 and G.723 (different from G.723.1)|
|G.729||8||Excellent bandwidth usage. Error tolerant. This one is better than other similar names, but it’s licensed, which means it’s not free. End users pay for this license indirectly when they purchase the hardware (phones or gateways) that implement it.|
|GSM||13||High compression ratio Free and available on many hardware and software platforms. The same encoding is used in GSM mobile phones (nowadays advanced versions are often used). It offers a MOS of 3.7, which is not a bad thing.|
|iLBC||15||Tripods Internet Low Bit Rate Codec. it’s now acquired by Google and it’s free. Strong packet loss, it is used by many VoIP applications, especially open source.|
|Speex||2.15 / 44||Minimizes bandwidth usage with variable bit rate. This is one of the most preferred codecs for many VoIP applications.|
|SILK||6 to 40||SILK was developed by SkyK and is now licensed because it is an open source freeware that has made many other applications and services available for use. This is the basis of the latest Opus codec. WhatsApp is an application that uses the Opus codec for voice calls.|