[Serusers] Mediaproxy in public IP e two client behind same Nat

[pistara_bros at tin.it]

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.