asterisk users - Jan 2007 - low audio (sometimes)

Hi all,

I am using asterisk 1.2.14 release on a 3GIG box/1 GIG RAM with a 
TDM2400E card.
For the most part my echo problems are gone (I have not noticed any issue).
The problem I have is SOMETIMES I get really low audio.
This typically happens when a call is coming in to the TDM2400E card
and going back out the same card to my cell phone.

My card is alone on its interrupt.

What might I look at or try to fix this issue?

Thanks

Jerry