Noisy audio on Yealink phones
When users of Yealink telephones hear their interlocutors disturbed (muffled voice, with echo, or intermittent), and the usual analyzes (network, connectivity, VoIP operators, Codec negotiation) do not highlight any anomalies, the cause could be the setting of the phone itself.
Yealink phones reproduce the speaker’s voice locally to avoid the annoying “empty” effect: the ear plugged by the handset, in fact, is unable to fully hear one’s own voice and the resulting effect resembles a feeling of emptiness for some bothersome. This replica of one’s voice obviously has a volume and in some cases the union of this signal with one’s own echo or the voice of the external interlocutor can disturb the voice of the interlocutor himself. Usually the deactivation of the echo canceller or the CNG (confortable noise generation) has no effect, because the replication is generated locally, independent of the SIP protocol.
In this case you can try to change the volume of this local replica in the phones configuration. Here are the directions:
- Update the firmware to the latest version
- Enter the Settings-> Configuration menu
- Under Export CFG configuration file select All Settings and export the file
- Open the file with Notepad / Wordpad (NOT with Notepad), if the voice.side_tone parameter is not set, insert the line voice.side_tone = -21
- If the parameter is already present and set to a value other than -21, set it to the value -21.
- Save the file, return to the web interface and use the file import in the same menu as before under the Import configuration CFG file item.
As mentioned, the side_tone parameter adjusts the volume of the replica of your voice, the value -21 is an optimal value, but you can try lower values (-26, -30, etc.) as long as the “empty” effect does not prevail described above.