One way audio again and again and again

hi everyone
i tried "asterisknow and pbx in aflash " and i made all things to resolve one way audio problem but i still have it now iam using asterisknow can any one tell my whats the best way to make a call to extenal phone with NAT .

Just so you know, there are certain router models (especially older ones) that seem to have a real hard time with VoIP traffic. But that said, take a look at this page: HOWTO: Resolving Audio Problems

What about “D-Link wireless dsl 2640u” good for voip or bad , and what about "ATA hanlong unicorn2002 " good or bad ?