How to increase sound card volume

As shown in the extension.conf weDial the Console/dsp.

exten => _X.,1,Answer
exten => _X.,2,System(/usr/sbin/xxxx ‘CALL~’${EXTEN}’~’${CALLERID(name)}’~’)
exten => _X.,3,Dial(Console/dsp)
exten => _X.,4,hangup

How can I increase the tx and rx volume level?
Asterisk version is 1.4.26

Best Regards

did you try to use “system” mixer utilities?

Yes, I did as
#amixer set Master 100%
already but want to increase the amplitude of the sound packets in asterisk because we use two different handsets, one of them’s the volume level is high so the sound at the (Console/dsp) is good, but the other’s volume level is low so the sound at the (Console/dsp) is bad.

Because of that we want to adjust the sound level via asterisk.