[OpenSIPS-Users] PRACK interworking requirements

Wed Nov 26 09:55:52 UTC 2025

Hi,

I believe we need more details on how to handle UPDATE compared to
Re-INVITE or PRACK/100rel. The major differentiator is that an UPDATE can
happen prior to the session being accepted, e.g. you could change your
codec after sending the initial INVITE and before the B-Party accepts the
call.  I always wanted to check if I could implement a local "UPDATE"
Generation in the b2b-modules, as it would allow us to handle
preconditioning (as in VoLTE) locally. However, I haven't had the time to
dig deeper into this yet.
I've also seen UPDATE used to verify a session-keep-alive, which should
only be answered and not further processed.

Probably, we can do something more clever than Oracle ;-)

Just thinking out loud,
Carsten
--
Schöne Grüße aus Hamburg, dem Tor zur Welt,
Carsten Bock

Baron-Voght-Str. 128a I 22607 Hamburg I Germany
T +49 179 2021244 I carsten at bock.info
LinkedIn: https://www.linkedin.com/in/carstenbock/

Am Mi., 26. Nov. 2025 um 09:37 Uhr schrieb Johan De Clercq <Johan at democon.be
>:

> Update support would also be handy. For ease of use there should be update
> to reinvite (update is a massive problem).
> as you like the oracle documents, here is a link
> https://docs.oracle.com/cd/E95618_01/html/sbc_scz810_acliconfiguration/GUID-17824ABA-36FE-4E50-A6EB-F3BADEA9767E.htm
> .
>
> I implement this feature everywhere.
>
> -Johan.
>
> Verzonden vanuit Outlook voor iOS <https://aka.ms/o0ukef>
> ------------------------------
> *Van:* Users <users-bounces at lists.opensips.org> namens Bogdan-Andrei
> Iancu <bogdan at opensips.org>
> *Verzonden:* Wednesday, November 26, 2025 8:59:10 AM
> *Aan:* OpenSIPS users mailling list <users at lists.opensips.org>; Vlad Paiu
> <vladpaiu at opensips.org>
> *Onderwerp:* Re: [OpenSIPS-Users] PRACK interworking requirements
>
> Hey Vlad,
>
> Yeah, the function is a good starting point, but maybe for internal usage,
> either with a wrapper on top or in an auto mode, in order to take care of
> all 100rel specifics.
>
> Regards,
>
> Bogdan-Andrei Iancu
>
> OpenSIPS Founder and Developer
>   https://www.opensips-solutions.com
>   https://www.siphub.com
>
> On 25.11.2025 18:23, Vlad Paiu wrote:
>
> note that we currently have
> https://opensips.org/html/docs/modules/3.6.x/dialog.html#func_dlg_send_sequential
> , it can be used to generate a PRACK ( you'll have to manually add the Rseq
> header), but it's not working properly if the upstream has multiple TO-TAGS
> that are ringing ( it will always generate to the newest learnt to-tag, and
> there's also some quirks with CSEQ mapping ), so perhaps the 'manual'
> approach would be getting dlg_send_sequential to work properly for
> generating early requests ( with PRACK being a rather specific use-case due
> to it's cseq/rseq stuff )
> On 11/25/25 13:14, Giovanni Maruzzelli wrote:
>
>
> On Tue, Nov 25, 2025, 11:57 Bogdan-Andrei Iancu <bogdan at opensips.org>
> wrote:
>
>
> 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?
>
>
> personally I'm a control freak and would like better an explicit function,
> maybe even with parameters to modify things if needed :))
>
> -giovanni
>
>
>
>
>
>
> 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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