Lab-XT telephone connection question

I was recently using the LAB-XT experimenter board found in my university lab for one of my final year project. (online schematic: http://melabs.com/downloads/LABXTSCH.PDF)
Everything works fine except the volume from the other side of the line is very soft while the input from the Mic is very loud. Unfortunately I am not too familiar with the opamp there.

i have been staring at the "Co Line Audio Amp" and wondering if there is anything I could replace there to boost the volume from the phone line without boosting the microphone locally?

Hope someone could suggest something I could try out.

Thank you in advance....

No one else has jumped in so I'll give it a go...

First, you don't say where you are "listening" to the sound from. Is it from the the "Line Out"? If so, do you have it plugged into an amplifier or are you using headphones or hanging a speaker off this line? If are not using an amplifier (something like some powered speakers will do) then naughty, you should know better...