Kamailio is making strides in handling media and transcoding but practically speaking that's still some ways away. It is true that "tweaking SIP headers" for interop is very much a fact of life. URI formats, URI parameters, caller id presentation types, etc, etc. However, at the point you're asking a B2BUA to pass a Proxy-Auth header from one leg to the next I think you should rethink your overall design and architecture... Of course all of these projects are open source and you're free to tweak/modify/mangle/break them any way you see fit and that's the beauty of open source. You just can't expect the developers that have to support this code for eternity to accept a patch that so clearly goes against the fundamental design of the software. FreeSWITCH is a lot of things but when it comes to bridging calls it's *always* a SIP B2BUA and that comes along with a fairly well (for SIP) defined definition for how multiple legs are handled. This is exactly why the descriptive term for Kamailio has moved from "sip proxy" to "sip server" over the years. On Thu, Apr 14, 2011 at 2:18 PM, Dave Horton <dave@dchorton.com> wrote:
In my case, I am trying to use it as a simple transcoding server. And the rich media support of codecs, and the ease of managing multiple sip profiles and setting up a back-to-back user agent scenario lend themselves quite well to the task IMO. I don't think the other solutions handle media or transcoding at all (correct me if I'm wrong) so trying to build the solution using those platforms would actually leave quite a lot of heavy lifting to do.
I have built a lot of SIP apps over the past 10 years, on a lot of different networks, and I have found that it is critical to be able to tweak SIP headers to make these interop. I wish it weren't the case, but it has been and still remains so. FS seems to only allow true custom headers (e.g., X- headers) to be manipulated at this level, and I find it to be a shortcoming.
-- Kristian Kielhofner