Hello Team.
We all agree that PRACK should be supported by the end devices and all agree that PRACK should be supported in order IMS to provide some services. So what is actually happening now on Carrier to Carrier interconnection is the following. In order to be able to interconnect on a carrier exchange, you should comply with a set of specifications. One of those is the PRACK/100rel support. That means that you, as a carrier, must either force your customers to enable PRACK, or do an interworking in the middle. The first option is not feasible as you might have end devices that are not supporting PRACK hence you should find a way to interwork with a device in the middle. That is why several vendors have implemented modules for PRACK interworking, like bellow <https://docs.oracle.com/en/industries/communications/session-border-controller/9.1.0/configuration/sip-prack-interworking.html> https://docs.oracle.com/en/industries/communications/session-border-controller/9.1.0/configuration/sip-prack-interworking.html I believe that the feature is needed and ideally should be implemented on proxy level. I am willing to contribute on that as this feature is critical for our business. Regards Antonis From: Users <[email protected]> On Behalf Of Aleksei Vasilev Sent: Παρασκευή, 14 Νοεμβρίου 2025 12:00 To: OpenSIPS users mailling list <[email protected]> Subject: Re: [OpenSIPS-Users] 100rel / PRACK Interworking Hi colleagues, It’s worth mentioning that PRACK (and 200 OK for PRACK) often participates in SDP offer/answer negotiation (RFC 3262, RFC 6337). I’m wondering how this can be implemented solely on the SIP proxy side? — Alexey Vasilyev 14 нояб. 2025 г., в 10:39, Johan De Clercq <[email protected] <mailto:[email protected]> > написал(а): pfff, indeed. you save a tiny little bit of networking traffic, that's the only thing that I see. okay, so the module should contain - 200 OK'ing prack. - (be able to send prack (?, if there is a use case)). - handle update (via rtpprxoy and rtpengine). Op vr 14 nov 2025 om 10:33 schreef Giovanni Maruzzelli <[email protected] <mailto:[email protected]> >: > 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 <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> >: 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 <[email protected] <mailto:[email protected]> > Im Auftrag von Johan De Clercq Gesendet: Donnerstag, 13. November 2025 16:29 An: [email protected] <mailto:[email protected]> ; OpenSIPS users mailling list <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> >: 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 <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> > Sent: Πέμπτη, 13 Νοεμβρίου 2025 16:37 To: [email protected] <mailto:[email protected]> ; OpenSIPS users mailling list <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> > wrote: eg: https://lists.opensips.org/pipermail/users/2024-March/047880.html On Thu, Nov 13, 2025 at 3:27 PM Giovanni Maruzzelli <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> > 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 _______________________________________________ Users mailing list [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users -- 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 [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users _______________________________________________ Users mailing list [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users _______________________________________________ Users mailing list [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users -- Sincerely, Giovanni Maruzzelli OpenTelecom.IT cell: +39 347 266 56 18 _______________________________________________ Users mailing list [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users _______________________________________________ Users mailing list [email protected] <mailto:[email protected]> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
_______________________________________________ Users mailing list [email protected] http://lists.opensips.org/cgi-bin/mailman/listinfo/users
