[SR-Users] MESSAGE is not successfull in Kamailio IMS

Hi All, I installed kamailio on Ubuntu as IMS pCSCF/iCSCF/sCSCF. REGISTER is fine, but when I tried to send a MESSAGE (SMS) from one user to another, it was always not successful. I captured IP packets on the server, and it seemed that the error was caused on pCSCF. User1 and User2 are both behind their NAT network. Suppose User1's private IP is Private_IP1, and User1's public IP (on router) is Public_IP1, and User2's private and public IPs are Private_IP2 and Public_IP2: User1 pCSCF iCSCF sCSCF user2 MESSAGE ----------------> MESSAGE ---------------------> MESSAGE -------------------> MESSAGE <----------------------------------------------------- MESSAGE ---------------------------------------------------------------------------- ----> Unfortunately, from the captured data on the server, in the last step, the MESSAGE was sent to the Private_IP2 of User2. It should be sent to the Public_IP2. Of course, the datagram with the destination of Private_IP2 cannot reach User2 successfully. Please help analyze why the pCSCF sent the MESSAGE packet to User2's private IP instead of public IP. The configuration file was attached for reference. BR. Thierry Luo