[OpenSIPS-Users] PRACK interworking requirements

[Bogdan-Andrei Iancu]

Hey all and A Happy New Year !

Pocking again the topic.... based on the discussion, I see two 
approached (they do not exclude one each other):

a) manual - to generate the PRACK explicitly from script, when handling 
a reply. As Vlad mentioned, maybe something based on 
dlg_send_sequential() (but tricky when handling multiple branches / 
to-tags from upstream). Answering to a PRACK can be done even now, so 
not a problem. Also inserting the related Supported / Requires hdrs, 
again, can be done from script.

b) auto-mode - to be transparently provided by the dialog module. To be 
activated by a create_dialog() flag, resulting in auto generating the 
PRACKs (based on the hdr's in the reply). The module should be also 
responsible of replying to the PRACK requests and to adjust the hdrs too.

Does this sound like a plan ?

Regards,

Bogdan-Andrei Iancu

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

On 25.11.2025 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
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>
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