Request for examples of providers requiring things that chan_pjsip cannot provide

I commented on the FreePBX forum that, when I suggested, here, that people should be moving to chan_pjsip I’ve had that challenged, for reasons other than TEL: URIs. I believe the reasons related to providers insisting on non-standard use of headers.

I’ve now been challenged to provide details of those reasons. Especially if you have challenged me on this I would appreciate either details of problem cases, or a link to one of the challenges. Even, better, would be if you could reply to FreePBX Roadmap for Chan_SIP Removal - #11 by BlazeStudios - Development - FreePBX Community Forums so I don’t have to be a middle man, if people challenged the validity of the reason.

When I changed to pjsip was very hard, but now I see its was a best choice.

I’ve changed the subject to try and make the question clearer. I’m after things that people have previously reported as blocking a move to chan_pjsip, not surmountable difficulties. Currently that includes providers who require TEL: URLs to be accepted, although I understand that partial support is now in the pipeline, but I remember people saying there are other unusual uses of SIP that chan_pjsip cannot currently handle but some providers insist on.

I did try to find the old threads, where my suggesting to move to chan_pjsip was challenged, but I couldn’t find good search terms, and I’ve posted a lot here, so a brute force search is going to be difficult.