[OpenSER-Users] newbie questions

[Alex Balashov]

Doug,

Doug McLetchie wrote:

> I've been reading manuals & sip specs all day, and I think that I found 
> my answer, and it really is an easy one.  here's my own answer to my 
> question, can you let me know if this sounds right?
>  
> When a message is send from a user agent (on the public internet) to my 
> gatweway & then to the proxy (on a private network), the gateway will 
> add a via on to the message.  that's how open SER (or any other proxy) 
> can send a response message back to user agent on the public internet 
> via the gateway.
>  
> It's really the same thing as setting up a registrar, or any other kind 
> of proxy/user agent that's going to communicate via a SBC of any kind.  
> So, it that right?  is that how the SIP via header is used?

   The Via: header is used to indicate to the receiving endpoint / next 
hop the route the message took to get there.  In and of itself, it does 
nothing to require that the message be passed back through any of the 
intermediate elements detailed in the Via: header stack - by default, it 
will circumvent it and go back to the endpoint associated with the 
source URI.

   If you want to capture the responses at the proxy as well, that is 
done by having it append a Route: field, which instructs the receiving 
endpoint that all further messages in this dialog should be relayed back 
through it.  In OpenSER, that is done with record_route().

Cheers,

-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
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