Hi to All, I'm investigating again about Mediaproxy and SER , but in this test i'm using the the testbed of smile.ing.uniroma1.it whic use SER and Mediaproxy in a public ip 151.100.122.144 I'm using Client_A (X- lite) running on WindowsXP 192.168.123.10 and Client_B (X-lite) running on WindowsXP 192.168.123.168 My Lan use a router with a public ip 83.211.41.253 So the clients are behind the same Nat. Using ethereal i see that during the conversation the RTP packet dont' pass through the Mediaproxy in public ip (151.100.122.144) but the packet go directly from one computer to another of my Lan. So the question is : what SER architecture (with Mediaproxy or with SEMS or other..) i have to use in order to have a proxy RTP that work as man in the middle and manage all RTP Traffic between the two clients? Please help me. thanks.