Sound Volume problem

[James_Yealink]

Hi Ibercom,

If 4 of them all have the issue it should not be a hardware problem.
When problem happens you can't hear voice through both handset and speaker? Or just one of them can't hear voice.
The problem happens in every call or randomly?
If you do a hold/reume operation can you hear voice again?
The voice goes progressively down but disappear suddenly?

Please try a firmware upgrading to V73 version.
http://www.yealink.com/Upload/UCOne/2015...3.0.50.zip

If the problem persist, try a reset and check again.

Regards,
James