[Serusers] Three NAT case!

[szj]

  During the testing procedure, I found that when both sip UAs
who are located behind the same NAT cloud want to establish
voice or video connection, there is not neccesary to bridge
them with rtpproxy. Only in situations where one of UA sits
behind NAT or each UA sits behind different NAT clouds, that
need a RTPProxy to bridge their media stream.
  What I mean is SER can determine the use of RTPproxy or not
through the registration of sip UA. In location table, there
are recieved and contact fields. But ser don't fill the
recieved field, I think it is very userful for NAT.

    Glad to hear your instructions
   
    Best Regards
 
Sun Zongjun