Why so much difference ??

I am TIRED of one issue with Vici.
I use g729.
I have configured my Xlite with cc101.
When I directly dial using my xlite as 911+ 10 digit USA number, Qlty is awesome.
When I log in to the agent screen and take calls predictively, volume is very low.
I tried using VoiceTime, there was a difference but not drastic.
Then why there is a drastic difference in sound qlty , even if both uses same asterisk , same bandwidth,same VOIP, same xlite, same login ?
I use g729.
I have configured my Xlite with cc101.
When I directly dial using my xlite as 911+ 10 digit USA number, Qlty is awesome.
When I log in to the agent screen and take calls predictively, volume is very low.
I tried using VoiceTime, there was a difference but not drastic.
Then why there is a drastic difference in sound qlty , even if both uses same asterisk , same bandwidth,same VOIP, same xlite, same login ?