Hi,
I wanted to raise the possibility of an inline signalling-only B2BUA component to Kamailio.
I know that's an extremely poor fit for Kamailio, and not at all what it's supposed to do. And there are many things about the OpenSIPS B2BUA module that reveal how awkwardly it is situated, as a square peg in a round hole. I myself am philosophically opposed to a B2BUA in Kamailio to the threshold of physical violence.
However, the reason I bring it up for discussion is that there are very few viable, high-performance signalling-only B2BUA alternatives that are FOSS. There is enormous demand for a B2BUA, mainly for topology concealment purposes, from the short-duration traffic industry, which many users of Kamailio deal with. It's why a lot of them end up going to OpenSIPS; they need the B2BUA, and prefer to consolidate on one OpenSER brand.
Anyone who has tried to run high-CPS traffic through the existing FOSS signalling-only B2BUAs out there situated in front of Kamailio has discovered, sometimes in a very financially painful way, that:
- FreeSWITCH falls over at around +/- 300 CPS.
This is with RTP relay disabled -- signalling-only. It requires horizontally scaling a large number of FreeSWITCH boxes to meet a capacity requirement of, say, 2000 CPS, which is unfortunate given the favourable proposition offered by Kamailio for the infrastructure unit economics. In other words, it's ironic to have to build a fleet of 10 FreeSWITCH boxes for the 1% problem of topology concealment when Kamailio can otherwise churn through 2000 CPS with no issues.
- SEMS' 'sbc' module is a good candidate and can handle the load, but Frafos offers practically no support for it, with all efforts focused on their commercial ABC SBC product. That's very understandable, but just not practical given the high technical knowledge SEMS requires to deploy and maintain in this capacity.
- None of the other userspace B2BUA folk traditions can handle the load.
So, like I said, I personally recoil in shock and horror at the idea of introducing a B2BUA into something that was designed to be anything but a B2BUA. But, there is a huge market opportunity for this functionality in North America, and at the moment, users who need it are mostly ending up in OpenSIPS land.
-- Alex