Open Source Session Border Controller

At the edge of a VoIP network, the session border controller is what decides which calls get in, hides your internal SIP topology, and bridges the incompatible signaling that real-world carriers throw at you - it is the firewall and translator your voice traffic cannot work without. The open source SBCs here put that border under your control, so call routing, security policy, and how SIP is normalized at the perimeter are configuration you own rather than features gated behind a telecom appliance.