[Serusers] NAT NAT..and a little more NAT

[hwang at ecs.csus.edu]

I'm a little confused.
Correct me if I'm wrong.  If STUN is used, the UA find out what kind of 
NAT it's behind by talking to the STUN server.  Then the UA modify the 
address/port send to proxy server depend on the STUN query result.
The proxy server doesn't need to know the existance of the STUN server.
The STUN server's only purpose is for the UA to figure out it's "location."
So, the term "go through STUN" is confusing me.  The SIP packets doens't 
go "through" STUN, then to proxy.  It should go directly to the proxy.
Please clear me out, thanks.