7.7 Identity Caching Function

33.1273GPPLawful Interception (LI) architecture and functionsRelease 18TS

7.7.1 General

The ICF is responsible for receiving identity caching events from all IEFs in the network over the LI_XER interface and handling queries from the IQF over the LI_XQR interface to the IQF as defined in clause 5.7.

The temporary cache duration shall be configurable by the LICF on a per CSP network basis.

NOTE: The terms identifier and identity are used interchangeably in clause 7.7. This also applies to the naming of functions like IQF.

7.7.2 ICF Query Identities

The IQF present in the ADMF shall be able to query the records held by the ICF using one of the following target identifiers:

– SUPI.

– SUCI.

– 5G-S-TMSI.

– 5G-GUTI.

NOTE: Targeting based on GPSI, PEI, IMS identifiers or other legacy identifiers (e.g. MSISDN) is not supported by the present document.

The list of event parameters is specified in TS 33.128 [15]. Each event shall include at the minimum the following information:

– Query target identifier.

– Time of target identifier observation.

For queries based on temporary identifiers the following additional information shall be included:

– Tracking area identifier.

– Cell identity.

7.7.3 ICF Response parameters

The list of event parameters is specified in TS 33.128 [15]. Each event shall include at the minimum the following information:

– Subscription permanent identifier.

– Related temporary identifier(s).

– Start of validity timestamp(s).

– End of validity timestamp(s).

The following additional information shall be included if it was available in the IEF records provided to the ICF:

– Permanent equipment identifier (PEI).

– Generic Public Subscription Identifier (GPSI).

The following additional information shall be included when available and if requested in the IQF to ICF query:

– Location information (i.e. Cell identity and tracking area identifier).

7.7.4 Network topologies

Since the ICF caches events independently of network topology for individual service usage UEs, no specific network topology handling is provided by the ICF. The IQF shall be responsible for handling any network topology requirements that may be applied by the LEA in an individual warrant.