In order to disable the Call Waiting tone on a second call the following parameter needs to be changed:
call.callWaiting.ring
Explanation from the admin guide:
Specifies the ringtone of incoming calls when another call is active. If set to Null, the default value is beep.
Possible values are: beep, ring, silent
If this is set to ring the Call Waiting will be played via the Phones Speaker.
An example file which turns the Call Waiting tone Off is attached and after being unzipped can be imported via the Web Interface as described => here <=
If official support is required please check how to phone or open a case here
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