How to increase TX/RX gain for SIP calls

I am new to AsteriskNow FreePBX community.
I have setup Asterisk Now 1.7 on Intel core2duo system dedicated for this server. Using the freePbx GUI I have configured few sip extensions and using x-lite soft phones I am testing the whole system.

So far I have been able to successfully establish calls but the voice is very low and bit distorted so I need to know how can I increase the audio gain and improve the voice quality for Sip calling.

I have configured my server with a static IP but for internet we have to use proxy so how can I enter proxy settings in the AsteriskNow server??

thanks in advance

It sounds like you may have issues with your equipment or the far end equipment calling you.

There are no options to amplify the signal (beyond the volume control on your phone).

I am using two laptops with headsets to talk to each other and there are located in the same building connected to the server via LAN.
I have even used two different softphones i.e x-lite and 3CX but the result is the same.

Do you have a solution to enable proxy settings on my AsteriskNow server since I am not able to connect to update or receive my voicemails.

Umer Hamid