SBC Manager — System Overview

What Is a Session Border Controller?

A Session Border Controller (SBC) sits at the border between your private VoIP network and external networks — carriers, remote offices, internet-connected endpoints. It controls, protects, and transforms SIP sessions crossing that boundary.

The SipLive SBC acts as the secure demarcation point between carrier trunks and the PBX. All SIP traffic passes through the SBC — the PBX and internal extensions are never directly exposed to the public internet.

Core SBC Functions

• Security — drops SIP from unknown sources (the firewall automatically allowlists only enabled trunks' IPs), enforces destination fraud rules, and hides internal topology (B2BUA / topology hiding).
• NAT traversal & media anchoring — resolves NAT issues and anchors RTP so audio always flows (see SBC Manager — NAT Traversal and Media Handling).
• Interoperability — header manipulation rule sets (HMR) normalize SIP between carriers and PBX systems that implement SIP differently.
• Routing — priority-ordered destination and source prefix policies with automatic failover, plus per-DID inbound routing.
• Capacity & licensing — per-trunk channel caps and a licensed concurrent-call limit.

The Appliance

SipLive SBC Manager runs as a hardened Debian 12 appliance: Asterisk 20+ (PJSIP) as the SIP engine, MariaDB for configuration, and a web GUI for all management. It installs from a self-contained offline ISO (see SBC Manager — Installing the Appliance).

The Staged Apply Model

The most important operational concept: changes never touch the live SIP engine directly. Trunks, routes, DIDs, HMR, and fraud rules are staged in the database; the Apply workflow shows a diff of exactly what will change, then writes the generated Asterisk config and reloads. Every apply creates a numbered version with one-click rollback. See SBC Manager — Config Apply, Scheduling, and Rollback.

Where Things Live in the GUI