> 6.3 | Adjusting the Volume

> There are several ways to adjust the volume of the connected audio devices. Each audio mode uses 5 volume steps, which can be selected with the parameters <outStep> or <level>. The steps can be set with the following commands (where <outStep> or <level> are identical).
> AT^SNFV=<outStep>
> AT+CLVL=<level>
> AT^SNFO=<outBbcGain>,<outCalibrate[0]>,...,<outCalibrate[4]>,<outStep>,<sideTone>
> The values of the 5 volume steps <outStep> and <level> can be specified with the parameters <outCalibrate[0]> …<outCalibrate[4]> of the AT^SNFO command. Table 6 contains the module’s factory settings.
> Because of the approval requirements in audio mode 4 (User Handset) regarding side tone, the use of AT^SNFO is suggested for this mode. See example in Section 6.3.2.
> No matter which command you use to set the volume, the selected step (<outStep> or <level>) will be stored non-volatile when the GSM module is powered down with AT^SMSO or reset with AT+CFUN=1,1.
> Users should be aware that the selected volume step is a global setting, i.e. when selecting another audio mode with AT^SNFS the value of <outStep> or <level> does not change. This is also true for mute operation, which will be retained when you switch back and forth between different audio modes. To mute the microphone you have two commands: AT^SNFM and AT+CMUT.

> Table 6: | Default values of audio modes (subject to change)

> Mode | Default settings (to be queried with AT^SNFO?)
> ^SNFS=1 | ^SNFO=1,16384,16384,16384,16384,16384,4,6878 (no steps)
> ^SNFS=2 | ^SNFO=2,4096,5792,8192,11584,16384,4,0 (3dB steps)
> ^SNFS=3 | ^SNFO=1,4096,5792,8192,11584,16384,4,8192 (3dB steps)
> ^SNFS=4 | ^SNFO=1,4096,5792,8192,11584,16384,4,6878 (3dB steps)
> ^SNFS=5 | ^SNFO=0,4096,5792,8192,11584,16384,4,0 (3dB steps)
> ^SNFS=6 | ^SNFO=0,4096,5792,8192,11584,16384,4,0 (3dB steps)