Increase or decrease audio level for a channel's incoming (read) audio stream our outgoing (write) audio stream.
This allows you to alter the volume of the call and make it louder or quieter.
The first example increases the audio level on the inbound audio stream and the second example decreases the level on the outbound audio stream.
read and write can take integral values from 4 to -4
The audio levels for this dialplan application correspond to the levels found in the conference application, namely -4 to 4.
In digital audio it is not optimal to modify the audio stream at the server level. It is almost always better to adjust the volume at one of the analog points, like the phone, headset, or analog TDM card. This dialplan application is available to assist the user who has broken devices that can't or won't adjust their audio.