X2 (LI) (Lawful Interception X2 Interface — Intercept Related Information)

Also known as: LI X2, X2 LI interface

X2 is the ETSI lawful-interception interface (TS 103 221-2) that carries Intercept Related Information (IRI) — signalling events such as call setup, SMS metadata, session establishment and location updates — from the POI/MF to the Law Enforcement Monitoring Facility. It is distinct from the 3GPP X2 handover interface between eNodeBs and is transported inside a dedicated LI network.

Categories: Threats and AttacksProtocols and StandardsRegulation and Compliance

X2 (LI) in context

Telecom threats range from opportunistic SMS phishing and SIM swap to nation-state grade location tracking and lawful-interception abuse. The common thread is that most attacks exploit the inherited trust model of legacy signaling. SS7 and Diameter were designed for a closed operator community that no longer exists.

Telecom security is written into standards from 3GPP, GSMA, ETSI, IETF and ITU-T. Understanding which body owns which specification, and how the specs interlock (for example 3GPP TS 33.501 with GSMA FS.34 for 5G SBA security), is essential for both design and audit work.

To place X2 (LI) in the wider telecom-security picture, review X3 (LI), ETSI TS 103 221, X1, HI1, Mediation Device (Lawful Interception) and IRI.

Related terms

Equipment

Lawful interception systems (ADMF, mediation, HI1/2/3)

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