Session Border Controller (SBC)

A Session Border Controller (SBC) represents a crucial component (a physical device or a digital application integrated within a system) positioned along the perimeter of IP infrastructures to supervise and safeguard live communication interactions. Initially, SBCs were intended to deliver protection and oversee VoIP streams, although nowadays they operate across numerous categories of real-time connectivity, covering IP telephony, video meetings, chat services, and cooperative platforms.

An SBC functions as a specialized “boundary gateway,” guaranteeing reliable transfer of signaling plus media flows across multiple environments.

The Scheme of Operation of TrueConf Border Controller

Key Functions of SBC in IP Telephony and Multimedia

• • Topology hiding and network security

The SBC conceals the hidden network layout, operating like a unified ingress/egress hub for information. This enhances resilience, shields from DoS/DDoS intrusions, blocks telephony abuse, and guarantees encryption within signaling channels and media flows.

• • Protocol interoperability and interworking

An SBC may enable protocol conversion across various communication standards including SIP, H.323, WebRTC, and alternatives to maintain interoperability. It further strengthens connectivity through efficient NAT traversal.

• • Media and codec translation

SBCs can perform audio and video transcoding, negotiate formats and codecs between different systems, and ensure compatibility across subscriber networks.

• • Quality of Service (QoS)

The border controller examines link attributes, emphasizes multimedia streams, applies Call Admission Control (CAC), and provides consistent audio together with video performance.

• • Access control, accounting, and monitoring

An SBC executes authentication plus authorization of sessions, aggregates metrics with billing records, documents activities, and guarantees adherence to regulatory obligations.

SBC Vendors and Modern Solutions (2025)

• AudioCodes: Mediant portfolio series: ranging between smaller devices and ultra-capable carrier-level gateways with virtual SBCs.
• Ribbon Communications: Physical SBC appliances plus software-driven SWe platforms for business and operator infrastructures.
• Oracle: Acme Packet portfolio, extensively deployed across telecommunications ecosystems.
• Cisco: Cisco Unified Border Element (CUBE) integrated for ISR/ASR alongside Catalyst systems.
• Avaya: Session Border Controller for Enterprise (ASBCE), tailored specifically for Avaya Aura deployments.
• Others: Nokia, Mitel, Huawei, Genesys, TE-Systems (anynode), Metaswitch (Perimeta SBC), among additional suppliers.

The Role of SBC in Multi-Protocol Communications

• Security: Screens signaling plus media exchanges, thwarts intrusions, and ensures video with audio confidentiality.
• Interoperability: Transforms SIP, H.323, WebRTC, and resolves protocol variations.
• Quality of service (QoS): Manages capacity, restricts simultaneous call volumes, prioritizes streaming sessions, and tracks latency or packet failures.
• Codec translation: Executes transcoding while session attributes alignment
• WebRTC gateway: Links browser-based endpoints into SIP infrastructures, managing encryption together with codec alignment.

Choosing an SBC for a Hybrid Multimedia Infrastructure

When selecting an SBC, it is important to consider:

• Certification plus interoperability across the platforms being deployed.
• Implemented protection mechanisms (TLS, SRTP, anti-intrusion functions, access management);
• Media processing with QoS enhancements.
• Capacity and extensibility.
• Implementation method (hardware-based or software-driven SBC).
• Vendor assistance standards together with ecosystem reliability.