Enhance asterisk sound (louder)

Hi !
I use Record application to record the call but the sound is too low. I want to make it louder.
How can i do this?
thank you

Set the appropriate options.

However, if the volume is wrong, you likely have more serious problems as standard telephone codecs have limited dynamic range, and if the phones, or your FXO interface device, are not using the dynamic range properly, call quailty will be poor. Conversely, attempting to increase the amplitude of signals which are at the proper level, will exceed the recording dynamic range and cause clipping and severe distortion.

Note you will need to use MixMonitor, rather than Monitor, to vary the volume levels.