Trunk

A trunk is a high-capacity communication line that aggregates traffic between major nodes, historically inter-exchange voice trunks in PSTN, today SIP trunks for IP voice, MPLS uplinks between sites, and 802.1Q trunks carrying multiple VLANs between switches. Trunk security depends on the underlying technology; SIP trunks should use TLS and SRTP at minimum.

Categories: SignalingSecurity ControlsInternet and Routing

Trunk 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.

Security controls in telecom span signaling firewalls (SS7/Diameter/GTP screening at the network edge), transport encryption (IPsec, TLS, PRINS), identity and access on OSS/BSS, and monitoring at both the packet and log level. Controls are audited against GSMA FS.11/FS.19/FS.20/FS.36 and, in Europe, NIS2 sectoral rules.

To place Trunk in the wider telecom-security picture, review RCS, Diameter Interconnect Security, Lawful Interception, N32 Interface (5G), Network Exposure Function (NEF) and SS7 Interconnect Security.

Related terms

Related topic hubs

  • SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
  • Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • SEPP Security N32-c/N32-f, PRINS, JWE and OAuth 2.0 at the 5G roaming edge.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.