[OpenSIPS-Users] PRACK interworking requirements

Wed Nov 26 14:29:31 UTC 2025

hehehehe, UPDATE shmUPDATE :))

I was intentionally trying to keep it the simplest possible, but obviously
we have VoLTE and other IMS thingies coming...

Maybe we can do this in two steps, the first one just the basic PRACK to
keep ITSPs happy, and then the rest, as per Johan, Antonios and Carsten ?

On Wed, Nov 26, 2025 at 12:02 PM Carsten Bock <
carsten.bock.private at gmail.com> wrote:

> 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 (likely)
> 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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-- 
Sincerely,

Giovanni Maruzzelli
OpenTelecom.IT
cell: +39 347 266 56 18
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