[OpenSIPS-Users] Fwd: PRACK Interworking with OpenSIPs

[Bogdan-Andrei Iancu]

Hi Giuseppe,

Before trying to fix it somewhere in the middle (in a proxy), let me say 
this PRACK negotiation must be negotiated between the end-point. If one 
of the end points does not support Prack, it should notify that. In your 
case, the callee (sending 180 + required 180) must not request PRACK if 
there was not such capability advertised by caller in INVITE (via the 
Supported or Require header). Please see 
http://www.ietf.org/rfc/rfc3262.txt page 4:


    The rest of this discussion assumes that the initial request
    contained a Supported or Require header field listing 100rel, and
    that there is a provisional response to be sent reliably.


So, the PRACK support must be advertised by caller in initial INVITE, 
otherwise the callee must not use it. Could you check in your traffic if 
this is the case?


Regards,

Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com

On 14.07.2014 11:06, Giuseppe Cardone wrote:
> Hello,
>
> does anyone have any ideas regarding this issue ?
>
> Many thanks for any tips you may have.
>
> Kind regards,
> Giuseppe
> ------------------------------------------------------------------------
>
>     *Da: *"Giuseppe Cardone" <g.cardone at unidata.it>
>     *A: *users at lists.opensips.org
>     *Inviato: *Giovedì, 10 luglio 2014 15:11:54
>     *Oggetto: *PRACK Interworking with OpenSIPs
>
>     Hello,
>
>     I am trying OpenSIPs and would like to figure out if I can use it
>     to perform sip interworking between two UA's, one requiring PRACK
>     and another that doesn't support it.
>
>     In essence when OpenSIPs receives a 18x response with headers
>     "Required: 100rel" and "RSeq" from the called party, it should
>     initiate a PRACK request towards the called party itself, but, as
>     you might expect from a proxy, I don't see any function to do
>     this.  However, maybe someone with a better understanding of
>     OpenSIPs can tell me if it is available.
>
>     The b2bua module is were I was placing my hopes.  However, here
>     too I cannot see a way to initiate a PRACK request, or any request
>     apart from an INVITE (using the 'bridge' action) or a BYE (using
>     the 'end_dialog_leg').
>
>     Can anyone confirm whethere my conclusions on PRACK interworking
>     with OpenSIPs are correct and/or provide any ideas as to how this
>     may be accomplished ?
>
>     Many thanks,
>
>     Giuseppe
>
>
>
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