H323 IP Phone Problem

Hi,

Here i use an H323 v3 protocol IP phone. And i facing some problems here. The situation is like this, my company is use the private IP 10.x.x.x and i use a router to route the 10.x.x.x IP address to 192.168.1.x IP address. When i plug the IP phone into the 10.x.x.x segment i can use the phone without any problems. But if i plug in the phone behind the router with the 192.168.1.x IP address then the IP phone will not function properly. The problem which i facing is when i call out by using that IP phone, i just cannot hear the voice from the other side but when i speaking the other side can hear my voice clearly. Can anyone give some advice about this situation.

Thank you.