AGC on a phone conversation

I have a recorded conversation from an analog trunk. As usual one side 
is stronger that the other one.
In my case, the gap between signal levels are even bigger.


How does speex AGC preprocessor will perform on this type of audio 
recording?
Maybe I am wrong and AGC is not really what I need to equalize the two 
persons in my phone conversation?

As I Understand, AGC will perform better if each party is recorded in a 
different channel?

Thank you,

Yanick Bourbeau