Hi all: I am trying ser + nat module + rtpproxy case 1 UA 1 ---------------NAT1------------------ser/rtpproxy-------------NAT2---------------------UA2 192.168.4.2 61.228.9.233 61.228.9.66 61.228.23.191 192.168.2.10 rtpproxy run as rtpproxy,UA1 call UA2 case 2 UA 1 ---------------NAT1------------------ser/rtpproxy-------------NAT2---------------------UA2 192.168.4.2 61.228.9.233 61.228.9.66 61.228.23.191 192.168.2.10 UA1 call UA2 rtpproxy -l "61.228.9.66/192.168.5.1" (bridge mode) In case 1,when UA1 send ACK ,UA1 start sends rtp packet . and UA2 still not send rtpproxy will send to the port which UA2 original request in his SDP (like 1034) Obviously it's not correctly, and will be discard by NAT2 but after UA2 start send rtp packet to rtpproxy , rtpproxy will fix the correct port to send UA1's packet to NAT2 so NAT2 will relay it to UA2 But in case 2, after UA2 start send rtp packet to rtpproxy,rtpproxy did not fix the correct port, so rtpproxy still send UA1's rtp packet to incorrect port to NAT2 and the packet is discard by NAT2 , UA2 can't receive UA1's rtp packet Is this a bug? or something i need to configure more correctly ? Can anyone give me any idea about these ? Thanks in advanced Jimmy