I have installed SER 0.9.3.2  and media proxy 1.2.1 on the same machine.
The machine is on public network.
Calls work ok except when I have a UA on a LAN behind NAT calling to a UA that is in the same LAN.
In this case I get :
 
+----------+-------------------------------+--------------------------+
| username | contact                       | received                 |
+----------+-------------------------------+--------------------------+
| 22000001 | sip:22000001@192.168.1.7:5060 | sip:xxx.xxx.xxx.xxx:5060 |
| 22000002 | sip:22000002@192.168.1.6:5060 | sip:xxx.xxx.xxx.xxx:2557 |
+----------+-------------------------------+--------------------------+
 
The number that takes up port 5060 on the NAT server,which is 22000001 can call the other UA but not the other way round.
22000002 can only receive calls.
Please help me,
KM