Enforcing Policy Between Two Networks

There’s another element to the SIP architecture, a “session border controller.” This device incorporates a B2BUA or “back-to-back user agent,” plus a firewall and gateway. The B2BUA acts as a intermediary between two networks so that there is no direct connectivity between end-points. SBCs can enforce security policies, translate between dissimilar networks, and even support integration of two SIP devices using different SIP primitives to define feature sets.