How to fix it?Recording


I hope somebody can help me to fix recording problem,as it has bothered me for severl months.

I use AAH 2.8 and here is our Asterisk IPPBX network:

Softphone–(Lan)—Asterisk IPPBX----(Wan)—quintum—pstn cloud

I call out through SIP using G729.The quality of the call is great but the recording of the call is horrible,the sentences are overlapping,I also hear some noise like ?bo??bo?.

I also do another test:

Softphone-----Asterisk IPPBX-------Softphone

I call 201 from 202,both extentions are in my local network and they use ulaw,everything is ok, the quality of recording is great,no overlap,no noise.After then,I do the same except using g729,the conversation is also ok,but the recording is not good,sound is overlap after around one minute.

I?m no sure about the factors affecting the recording. Network envirement? Code selecting? Transcoding? Sox?

By the way,my hardware: Pentium D 3.40GHz , 2G RAM, Harddisk 74G 10000rpm

Any suggestions you can offer would be greatly appreciated!