Session Border Controller (SBC) (Session Border Controller)

Also known as: SBC

A Session Border Controller is a signalling and media element deployed at the edge of a SIP network (access side toward subscribers or interconnect side toward peers). It performs SIP normalisation, NAT and topology hiding, media anchoring, transcoding, DoS protection, and TLS/SRTP termination. In IMS, an access SBC often co-locates with the P-CSCF, while an interconnect SBC typically implements the IBCF/TrGW functions. SBCs are the primary enforcement point for VoIP fraud, toll fraud and telephony DoS controls.

Categories: SignalingRoaming and InterconnectSecurity Controls

Session Border Controller (SBC) in context

Signaling protocols carry the control-plane instructions that set up calls, register subscribers, hand over sessions and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA FS.11 / FS.19 / FS.20 as a top-tier telecom risk.

Roaming and interconnect are where two operators, often with an IPX or GRX carrier in between, exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place Session Border Controller (SBC) in the wider telecom-security picture, review Signaling Firewall, STP, SS7 Interconnect Security, SEPP Security, DEA and Detection Engineering.

Related terms

Equipment

Session border controllers (A-SBC, I-SBC, IBCF, TrGW)

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