[OpenSIPS-Users] PRACK interworking requirements

[Bogdan-Andrei Iancu]

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
>>>
>>>
>>>     _______________________________________________
>>>     Users mailing list
>>>     Users at lists.opensips.org
>>>     http://lists.opensips.org/cgi-bin/mailman/listinfo/users
>>
>>
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