Overlap problem in recorded calls

I use AAH 2.8 as my IPPBX.I am making calls through SIP using G723 and G729. My company is a callcenter and severl phones are needed to use recording funtion because of our client’s requriment. When I make calls,the quality of the call was great but when I hear the recording of the calls made that was horrible, the sentences were [color=red]overlapping[/color]. I think it’s not my machine?problem since I upgrade it before. Can any body help me to fix the problem? :question: