[Kamailio-Users] if client has stun support, does kamailio still needs to support NAT/rtpproxy ?

[Jinsong]

Hi, There:
  I have been wondering that , if client/phone has stun support, does kamailio still needs to support NAT/rtpproxy ?
in theory, when the client has stun support, it can find out its own public address and port, and from kamailio's point of view,
it just looks like the client is in the public internet. so kamailio should have no need to do NAT/rtpproxy.  without NAT/rtpproxy,
the bandwidth requirement on the kamailio is drastically cut down, because kamailio only needs to handle signal. 
  What I am not sure is , for the clients with sip support, will it constantly send out requests, say, every 2 minutes,
so the firewall won't expire the mapping of private/public address and port on the firewall itself. in case the client 
doesn't send out requests constantly, then the mapping may expire and that may present a problem. in that case, 
if we let kamailio send out OPTIONS every 1 minute to the client, then the mapping can be kept alive. if that is true,
then we will still don't need rtpproxy, thus saving bandwidth on the server and scales much better. 
  Is that I described true ? 

Jimmy