Interconnecting carrier SIP trunks and enterprise IPBXs looks simple on paper. In practice, it is one of the most expensive friction points in a VoIP infrastructure: you have to secure the IPBX exposed to the Internet, juggle several operators in parallel, fail over when one goes down, normalise routing — all without blowing the budget on a closed, opaque proprietary SBC.
PK-SBC is an open source answer to that problem. A Session Border Controller built on Kamailio, RTP Engine, Redis and PostgreSQL, designed along the KISS principle — Keep It Simple, Stupid — and battle-tested in production since 2012.