[OpenSIPS-Users] 100rel / PRACK Interworking

Fri Nov 14 09:30:01 UTC 2025

> It really is a mess, to me it seems that IMS guys are scared of rtp
+1 it is an endpoint thing, trunk providers are wrong to ask for it (what
do they get from it?)

when you (trunk provider) know that the phone is actually ringing, what do
you gain? It has meaning when you control the whole chain, end-to-end
(carriers, IMS) not at all for
deskphone->itsp->trunk->whatever->carrier->endphone

But I know they (trunk providers) start to *REQUIRE* PRACK

So, probably a module, or an extension of an existing module, can be
warranted and welcome

Possibly on 3.6.X (that's the last LTS of the 3.0.0 series)

Let's open a thread on what functionalities can be useful in it?

-giovanni

On Fri, Nov 14, 2025 at 10:21 AM Johan De Clercq <Johan at democon.be> wrote:

> +1.  I totally agree with you.
> It really is a mess, to me it seems that IMS guys are scared of rtp.
>
> Op vr 14 nov 2025 om 10:03 schreef Walter Schober <
> walter.schober at neotel.at>:
>
>> Hi!
>>
>>
>>
>> I also want to point out that its not done with PRACK handling alone.
>> Followup (multiple) UPDATE with codec changes must be handled, too.
>> Sometimes that lead into AMR(WB)/PCMA/G722/OPUS transcoding in early state.
>> Including all the DTMF PT issues.
>>
>> It is definitely a endpoint / softswitch feature.
>>
>>
>>
>> I know those ignorant IMS guys pushing out their internal mess to plain
>> RFC3261 interconnects and forcing tasks previously done by an MSC to the
>> rest of the world.
>>
>>
>>
>> Br
>>
>> Walter
>>
>>
>>
>> *Von:* Users <users-bounces at lists.opensips.org> *Im Auftrag von *Johan
>> De Clercq
>> *Gesendet:* Donnerstag, 13. November 2025 16:29
>> *An:* gmaruzz at opentelecom.it; OpenSIPS users mailling list <
>> users at lists.opensips.org>
>> *Betreff:* Re: [OpenSIPS-Users] 100rel / PRACK Interworking
>>
>>
>>
>> Giovanni on a side note, what to do with update ? do you handle it
>> locally or do you forward it to your endpoint ?
>>
>>
>>
>> BR, Johan.
>>
>>
>>
>> Op do 13 nov 2025 om 15:54 schreef Giovanni Maruzzelli <gmaruzz at gmail.com
>> >:
>>
>> Antonio, you may want to update this feature request from Johan:
>> https://github.com/OpenSIPS/opensips/issues/2076
>>
>>
>>
>> On Thu, Nov 13, 2025 at 3:48 PM Antonios Psaras <apsaras at microbase.gr>
>> wrote:
>>
>> Hello Giovanni
>>
>>
>>
>> I totally agree with you. PRACK is an endpoint feature. But as you know,
>> working with IMS, and having all kind or end point implementations of sip
>> stack you need to do the dirty job in the middle for interoperability
>> reasons. Commercial SBC have that feature called 100rel Interworking which
>> can be enabled per Trunk. Hence, if a carrier requires 100rel/PRACK
>> enforcement and the end point does not supporting it, the function is
>> engaged and handles the PRACK locally.
>>
>>
>>
>> I will check Bogdan suggestion but in the first read looks like a tmp
>> work around which I am not sure if that can be scaled to few hundreds of
>> CPS that we work with.
>>
>>
>>
>> As this is a feature that will be needed for VoLTE/5G/IMS networks my
>> suggestion is to create a module for that.
>>
>>
>>
>> Regards
>>
>>
>>
>>
>>
>> *From:* Giovanni Maruzzelli <gmaruzz at gmail.com>
>> *Sent:* Πέμπτη, 13 Νοεμβρίου 2025 16:37
>> *To:* apsaras at microbase.gr; OpenSIPS users mailling list <
>> users at lists.opensips.org>
>> *Subject:* Re: [OpenSIPS-Users] 100rel / PRACK Interworking
>>
>>
>>
>>
>>
>>
>>
>> El 26/02/2024 a las 7:43 a. m., Bogdan-Andrei Iancu escribió:
>>
>> >* yes, you can use the b2b_logic (together with b2b_entities) for that, *
>>
>> >* but it may be a too heavy tool for the purpose. Maybe you can try to *
>>
>> >* generate the PRACK from OpenSIPS level by using the t_uac_dlg MI *
>>
>> >* function [1] via the mi_script module [2] - basically to trigger that *
>>
>> >* MI cmd from the onreply_route, when receiving the 180 reply.*
>>
>> >
>>
>> >* [1] https://opensips.org/html/docs/modules/3.4.x/tm.html#mi_t_uac_dlg <https://opensips.org/html/docs/modules/3.4.x/tm.html#mi_t_uac_dlg>*
>>
>> >* [2] https://opensips.org/html/docs/modules/3.4.x/mi_script.html#afunc_mi <https://opensips.org/html/docs/modules/3.4.x/mi_script.html#afunc_mi> *
>>
>>
>>
>>
>>
>>
>>
>> On Thu, Nov 13, 2025 at 3:34 PM Giovanni Maruzzelli <gmaruzz at gmail.com>
>> wrote:
>>
>>
>>
>>
>>
>> eg: https://lists.opensips.org/pipermail/users/2024-March/047880.html
>>
>>
>>
>>
>>
>>
>>
>> On Thu, Nov 13, 2025 at 3:27 PM Giovanni Maruzzelli <gmaruzz at gmail.com>
>> wrote:
>>
>> Hello Antonio,
>>
>>
>>
>> PRACK is actually an endpoint feature, at the proxy level you can only
>> fake it...
>>
>>
>>
>> -giovanni
>>
>>
>>
>> On Thu, Nov 13, 2025 at 3:14 PM Antonios Psaras <apsaras at microbase.gr>
>> wrote:
>>
>> Dear Team
>>
>>
>>
>> As many carriers requires 100rel for interoperability reason with IMS,
>> the need for 100rel interworking is mandatory. Is there any solution
>> available to implement that on OpenSIPs Proxy level?
>>
>>
>>
>> Regards
>>
>>
>>
>> Antonis Psaras
>>
>>
>>
>>
>>
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>>
>>
>>
>>
>> --
>>
>> Sincerely,
>>
>> Giovanni Maruzzelli
>> OpenTelecom.IT
>> cell: +39 347 266 56 18
>>
>>
>>
>>
>> --
>>
>> Sincerely,
>>
>> Giovanni Maruzzelli
>> OpenTelecom.IT
>> cell: +39 347 266 56 18
>>
>>
>>
>>
>> --
>>
>> Sincerely,
>>
>> Giovanni Maruzzelli
>> OpenTelecom.IT
>> cell: +39 347 266 56 18
>>
>>
>>
>>
>> --
>>
>> 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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-- 
Sincerely,

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