[SR-Users] add fromuser to sip request

[Alex Balashov]

JR,

On 10/05/2010 02:00 PM, JR Richardson wrote:

> In Kamailio, how would I go about receiving a sip request, append a
> user "sipentry1" then forward it to Asterisk?  I would be using some
> sort of trunk prefix to identify which sip request to append the user
> like:
>
> 552145551212 at siprouter, strip 55, append user "sipentry1", dispatch
> t-relay to asterisk
> 562145551212 at siprouter, strip 56, append user "sipentry2", dispatch
> t-relay to asterisk
> 572145551212 at siprouter, strip 57, append user "sipentry3", dispatch
> t-relay to asterisk
>
> Any point in the right direction will be appriciated.  Which module
> should I be looking into?

In Asterisk, sip.conf peer matching is done by source host and port 
unless the 'type' is set to 'dynamic'.

That said, if your desire is to change the From header display name or 
user part of the From URI, you should use the 'uac' module and look 
into the 'uac_replace_from()' function.  It's a little unorthodox by 
RFC 2543 standards, but because it spoofs the From header statefully 
and reverts the value on replies before passing back to the near 
end--such that the initiating endpoint is none the wiser--it works.

Otherwise, if your main desire is to customise entry points into 
various dial plan contexts for otherwise similar calls, I suggest 
routing on a different criterion.  Custom headers have sort of become 
a de facto means of out-of-band inter-machine associated signaling 
additions in SIP where it is possible to add them.  Why not use a 
custom header?  In Kamailio, add a header to the initial INVITE 
request that is something like:

     append_hf("X-JR-Dialplan-Target: my_context");

Then, route all calls in Asterisk via one sip.conf peer and into one 
"master" dial plan context, where you can then make further routing 
decisions based on the value of the header - sip.conf:

     [my_proxy]
     ...
     host=xx.xx.xx.xx
     insecure=port,invite
     ...
     context=master_dp_router

And then in extensions.conf:

     [master_dp_router]

     exten => _.,1,Goto(${SIP_HEADER(X-JR-Dialplan-Target)},${EXTEN},1)

     ...

     [my_context]

     exten => 5551212,1,Answer
     exten => 5551212,n,Playback(hello-world)
     ...


-- 
Alex Balashov - Principal
Evariste Systems LLC
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