[OpenSIPS-Users] Fwd: PRACK Interworking with OpenSIPs

[Bogdan-Andrei Iancu]

Hi Giuseppe,

As proxy, it is a hard job to generate the PRACK requests. But the 
OpenSIPS B2B can do that - try to use the simples (the 
"topology-hiding") scenario and OpenSIPS b2b will automatically generate 
the PRACKs if "Require 100rel" is found in replies.

Regards,

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

On 15.07.2014 12:50, Giuseppe Cardone wrote:
> Hi Bogdan,
>
> Thank you for taking time to look at this issue.
>
> Your assumptions are all correct.  However, there are cases, such as 
> interconnect between operators, where PRACK is expected to be enforced 
> on the interconnect for all calls (this is the case for example of the 
> interconnects with Telecom Italia), ie outgoing INVITEs must always 
> present the header Supported: 100rel.
>
> In our case, our voip network and certain clients don't support PRACK.
>
> This is why I am trying to see if with OpenSIPs I can implement "PRACK 
> interworking", similarly to what commercial SBCs do.
>
> Do you have any suggestions as to if and how I may achieve this with 
> OpenSIPs ? My understanding as far as I can see is that currently this 
> is not possible.
>
> If so, just as a suggestion, you may want to consider features whereby 
> the b2bua module is expanded to allow Actions such as the sending of 
> additional SIP Requests such as PRACK and others, so that SBC 
> functionality may be implemented.
>
> Thanks again for your attention and the hard work you put into 
> OpenSIPs :-)
>
> Kind regards,
> Giuseppe
>
>
>
>
>
>
>
>
>
> ------------------------------------------------------------------------
>
>     *Da: *"Bogdan-Andrei Iancu" <bogdan at opensips.org>
>     *A: *"OpenSIPS users mailling list" <users at lists.opensips.org>, "g
>     cardone" <g.cardone at unidata.it>
>     *Inviato: *Martedì, 15 luglio 2014 11:02:10
>     *Oggetto: *Re: [OpenSIPS-Users] Fwd: PRACK Interworking with OpenSIPs
>
>     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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