[Asterisk-Users] Brief pauses during calls

[Mimmus]

Hi,
I'm experiencing brief pauses during my calls: 0.5-1.0 sec of silence if
call 
continues for more than a few minutes. 
I'm sure that problem is in the phone (a cheap ATCOM AT-320 with latest SIP
firmware) but I'd like to diagnose better.
During a little test, it seems that there is no problem with IAX2 firmware
(but there are others... I'm not able to transfer and pickup calls...)

Can I try different codec/jitterbuffer/othertrick?

Thanks
Mimmus