[Serusers] When to use MediaProxy

[tcchan]

Hi All,

I have SER work together with MediaProxy and two UAs; 

UA1 is NATED whereas UA2 has public IP.
 
I have something like this to process the INVITE

       if (client_nat_test("3")) {
           setflag(4);
       };
	
       if (isflagset(4)) {
            force_rport();							            fix_contact();
            use_media_proxy();
        };

        t_on_reply("1");
  


and on the reply_route, I have

      if (client_nat_test("1")) {
                setflag(4);
      };
      
      if (isflagset(4) && status=~"(180) || (183) || 2[0-9][0-9]") {
            if(search("^Content-Type: .*$")) {
		   	fix_contact();
                        use_media_proxy();
            }
        };



Now, if UA1 (nated) calls UA2, it is OK ( mediaproxy is properly setup
and both side can hear each other. The client_nat_test() is met and
flag4 is set which caused both the invite and the on_reply to
use_media_proxy).   

If UA2(public) calls UA1 (nated), problem arises, UA2 can hear UA1 but
not the reverse.  The client_nat_test("3") is not met and thus flag4 not
set.  On the reply_route, although client_nat_test("1") is met, flag4
set and use_media_proxy() is executed, it return 
 
error: use_media_proxy(): empty response from mediaproxy
ERROR: on_reply processing failed


To temporary work around this problem, I forcefully set flag4 on and
thus all calls route through the mediaproxy ( which is expensive in
bandwidth usage).

Is there any better way to solve this?

Any suggestion?

Has anybody already looks into this and has a solution?


Thanks for any help available.


Regards,

TC Chan