Audio Codecs

Audio Codecs

What is a Codec, what is the best one, and how do I set it on my VoIP phone?

What is a codec?

An audio codec (the term is a mashup of the words code and decode) is software that converts analog sound to compressed digital packets and vice versa. (A common audio codec is MP3.) The codec makes the data file smaller while preserving the quality of the audio.

Which Codecs does Voys support?
  • A-Law. Sometimes referred to as G711a, or PCMA
  • U-Law. Sometimes referred to as G711u, or PCMU
  • G.722
  • G.729
  • iLBC
  • Opus
What is the best codec to use?

There are three dimensions to consider when selecting the best codec for your situation:

  1. Call quality
  2. Bandwidth
  3. The level to which the codec can adjust compression to strike the optimal balance between bandwidth and call quality.

If your phone supports it, the best codec to use in most circumstances is Opus

Opus is a powerful codec that is able to optimize call quality by adjusting the compression to the available bandwidth.

The graph below illustrates this nicely in relation to some other popular codecs. The X-axis represents the required or used bandwidth, and the Y-axis represents call quality.


If your phone does not support Opus or if you'd like to experiment with other codecs, the following general guidelines can be used to select the best codec:

  • Fast and reliable internet connection with sufficient bandwidth freely available G722 or G711
  • Suboptimal internet connection (I.e. slow, variable speed, congested.) G729 or iLBC
  • Minimize data consumption with G729 or iLBC

💡 TIP: In some cases, your phone might require a firmware update to 'unlock' extra codecs.

Enabling extra audio codecs on Freedom

Make sure the codec you would like to use is enabled for your extension on Freedom.

  • Go to the 'Admin' tab on Freedom
  • Go to 'VoIP account'
  • Select the extension you would like to set up
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  • Click on the extension
  • Go to 'Advanced SIP Settings'
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  • Scroll down to 'Expert options'
  • The audio codecs A-law (G.711), G.722, iLBC, and G.729 are enabled by default
  • Select the audio codecs you would like to enable in the drop-down menu
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  • Click Save
Setting codecs on your Yealink phone
  • Press the ‘OK’ button to establish the current IP Address.
  • Copy the shown IP address in your web browser on your PC.
  • Press Enter
  • Fill in: Username: voys  Password: freedom (If your device is yet to be configured or has been factory reset the username and password will be admin)
  • Go to the 'Account' tab
  • Click on 'Codec'
  • PCMA and G729 will be selected by default
  • Click on Opus in the 'Disable Codecs' column
  • Click the right-facing arrow
  • Click the up or down arrows to change the order of codec selection
  • The sample rate can be changed by clicking the drop-down list
  • Click Confirm to save changes
💡PRO TIP: Optimise call quality further by setting Quality of Service (QoS).
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