[OpenSIPS-Users] PRACK interworking requirements

[Bogdan-Andrei Iancu]

Thank you Giovanni for starting this.

So, the feature should focus on generating the PRACK requests. Maybe 
this should be decoupled from the `100rel` management, as this can be 
received or locally inserted. And you can easily do it from script:
https://opensips.org/html/docs/modules/3.6.x/sipmsgops.html#func_list_hdr_add_option

The result here should be a dlg dedicated function to generate a PRACK 
from the onreply_route, like "dlg_answer_with_prack()" kind of function? 
or should we look into a more automatic approach, like flagging the 
dialog at creation to automatically generate the PRACK upon replies 
flagged with so?

Regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer
   https://www.opensips-solutions.com
   https://www.siphub.com

On 25.11.2025 11:46, Giovanni Maruzzelli wrote:
> hello OpenSIPSers,
>
> in previous mails has been noticed that various ITSPs are starting to 
> require PRACK support.
>
> We know that PRACK belongs to endpoints, specifically phones and B2BUAs.
>
> But...
>
> There can be a use case where OpenSIPS will work as SBC (not 
> necessarily using the b2b module)
>
> So, we can have a case where we would like to support that the 
> dialogue module insert the 100rel in the Supported: INVITE's header, 
> and manage to send a PRACK method to acknowledge provisional responses
>
> If and when 100rel/PRACK are "generated" by OpenSIPS, they will be 
> filtered out (not propagated) to/from the endpoints, even if the 
> endpoint would like to support it
>
> Reference RFC: https://www.ietf.org/rfc/rfc3262.txt
>
> I believe this will be enough to make ITSPs happy.
>
> Further developments can be moved to future.
>
> Would be very very nice to have this feature backported to OpenSIPS 
> 3.6, being it the last of the 3.X series, and an LTS
>
> Please let's gather here your thoughts , requests, corrections and 
> observations on this issue.
>
> Have a nice Monday you all!
>
> -giovanni
>
> -- 
> Sincerely,
>
> Giovanni Maruzzelli
> OpenTelecom.IT
> cell: +39 347 266 56 18
>
>
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