The present document describes the data content of a Lawful Interception interface in a TETRA system. It provides the
requirements and specification of the interface within a TETRA system for the purpose of providing data to Law
Enforcement Agencies (LEAs) in the area of Lawful Interception (LI) of communications.
The present document describes the internal LI interface of a TETRA network, and does not specify the means by
which data is delivered to the LEA or to its designated Law Enforcement Monitoring Facility (LEMF). However the
internal LI interface is defined in such a way that data may be carried transparently on most networks.
NOTE 1: In this context "internal" means within the boundary of the TETRA infrastructure. The boundary may
extend in such a manner that the TETRA LI function is remote from other components of the SwMI, or it
may be co-located with other SwMI components.
Figure 1: Model of TETRA interception
The general reference model of figure 1 shows that the overall LI interface lies between the LEMF and the TETRA
infrastructure (SwMI) and is composed of both the Handover Interface (described in ES 201 671 [8] and/or
TS 102 232 [11]) and the internal interception interface. The subject of the present document is the internal LI interface
that lies between the TETRA infrastructure and the mediation function.
The provision of a Lawful Interception interface for TETRA is a national option, however where it is provided it shall
be provided as described in the present document.
The Handover Interface may be the subject of national regulation and therefore the mediation function may be a matter
of national regulation.
The present document describes the data content of the information flows of the intercepted activity from the TETRA
system using ASN.1 but without respect to the encoding rules which are determined by the handover interface adopted.
The present document is structured as follows:
clause 4 outlines the essential requirements for the TETRA LI interface;
clause 5 presents the structural and behavioural models of the LI interface;
clause 6 presents the data model and allocation behaviour in the LI interface.