How to adjust volume?

Dear All,

I am running Asterisk 1.8.7, now, I can’t really hear the caller … , how to adjust volume?

please help

Thanks

Insufficient information. For SIP phones, consult the documentation for the phone. For dahdi analogue lines, consult the supplier of the interface hardware.

Hi,

sorry for the insufficient info, but what I meant is for FXO analogue lines.
I am going to try to set /etc/asterisk/chan_dahdi.conf

rxgain = 3.0
txgain = 3.0

do you have any idea or suggestion?

Thanks in advance

Regards

I assume these are sent to the hardware, so consult the hardware supplier.