[OpenSIPS-Users] 100rel / PRACK Interworking

Fri Nov 14 09:00:02 UTC 2025

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<mailto: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<mailto: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<mailto:gmaruzz at gmail.com>>
Sent: Πέμπτη, 13 Νοεμβρίου 2025 16:37
To: apsaras at microbase.gr<mailto:apsaras at microbase.gr>; OpenSIPS users mailling list <users at lists.opensips.org<mailto: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

> [2] 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<mailto: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<mailto: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<mailto: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
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