[Users] Who can help me to make it work when openser is behind NAT.

Hello, Everyone: I am newbie to openser. I would like to build a softwitch system by openser. It is work when client behind NAT, But it don't work when the openser server behind NAT where I add a DNAT rule in the router. Who can help me to address the issue ? FYI: CLEINT --------------------->Router ++++++++++++++++++++++++++++++ Openser 202.99.1.23 202.99.3.5 192.168.0.1 192.168.0.2 I use sipphone software to connect 202.99.3.5(5060) It don't work ... Jerry.