G.6.2.2 Interception

33.1283GPPProtocol and procedures for Lawful Interception (LI)Release 18SecurityStage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

G.6.2.2.1 IMS deployment

There are two deployment options for IMS for intercepting the service type of Messaging for SMS over IMS:

– Default.

– Alternate option.

It is expected that the CSP implements one of the two deployment options.

The conditions under which IRI-POI functions have to be provisioned are illustrated within the drawing and are further clarified in tables from G.6-3 to G.6-6.

G.6.2.2.2 LALS triggering

There are two deployment options for LALS triggering. It is expected that the CSP implements one of the two deployment options.

In LALS triggering option 1, the LTF present in the host NF that has the associated IRI-POI triggers the LI-LCS Client. In LALS triggering option 2, the LTF presents in the MDF2 triggers the LI-LCS Client.

G.6.2.2.3 Summary

Table G.6-2 provides the scope of NF domain that provides the IRI-POI/CC-POI/LTF functions for the service type of Messaging.

Table G.6-2: Scope of NF domain providing the LI functions for service type Messaging

NFs with LI function			Non-roaming	Roaming with LBO		Roaming with HR
NFs with LI function			Non-roaming	VPLMN	HPLMN	VPLMN	HPLMN
MMS Proxy Relay			IRI-POI	n/a	IRI-POI	n/a	IRI-POI
MMS Proxy Relay			CC-POI	n/a	CC-POI	n/a	CC-POI
SMSF			IRI-POI	IRI-POI	n/a	IRI-POI	n/a
MME (with SMS service)			IRI-POI	IRI-POI	n/a	IRI-POI	n/a
IMS NFs			See table G.6-3, table G.6-4, table 6.5 and table 6.6.
LALS triggering	Option 1	SMSF	LTF	LTF	n/a	LTF	n/a
		MME	LTF	LTF	n/a	LTF	n/a
		IMS NFs	See table G.6-3 and table 6.4
	Option 2	MDF2	LTF	LTF	LTF	LTF	LTF

Table G.6-3 provides the scope of NF domain in the IMS that provides the IRI-POI/LTF for SMS over IMS when the target is not a non-local ID with default IMS deployment option.

Table G.6-3: Scope of NF domain in IMS providing the LI functions for SMS over IMS (local ID) with Default

NFs with LI function			Non-roaming	Roaming with LBO		Roaming with HR
NFs with LI function			Non-roaming	VPLMN	HPLMN	VPLMN	HPLMN
P-CSCF			n/a	IRI-POI (NOTE 1)	n/a	n/a	n/a
E-CSCF			IRI-POI	IRI-POI	n/a	IRI-POI	n/a
S-CSCF			IRI-POI	n/a	IRI-POI	n/a	IRI-POI
LMISF-IRI			n/a	n/a	n/a	IRI-POI (NOTE 1)	n/a
LALS triggering	Option 1	P-CSCF	n/a	LTF (NOTE 1)	n/a	n/a	n/a
		E-CSCF	n/a	LTF	n/a	LTF	n/a
		S-CSCF	LTF	n/a	LTF	n/a	LTF
		LMISF-IRI	n/a	n/a	n/a	LTF (NOTE1)	n/a
	Option 2	MDF2	LTF	LTF	LTF	LTF	LTF

Table G.6-4 provides the scope of NF domain in the IMS that provides the IRI-POI/LTF for SMS over IMS when the target is not a non-local ID with Alternate IMS deployment option.

Table G.6-4: Scope of NF domain in IMS providing the LI functions for SMS over IMS (local ID) with Alternate option

NFs with LI function			Non-roaming	Roaming with LBO		Roaming with HR
NFs with LI function			Non-roaming	VPLMN	HPLMN	VPLMN	HPLMN
P-CSCF			IRI-POI	IRI-POI	n/a	IRI-POI (NOTE 2)	IRI-POI
IBCF			n/a	n/a	IRI-POI	n/a	n/a
LMISF-IRI			n/a	n/a	n/a	IRI-POI (NOTE 1)	n/a
LALS triggering	Option 1	P-CSCF	LTF	LTF	n/a	LTF (NOTE 2)	n/a
		IBCF	n/a	n/a	LTF	n/a	n/a
		LMISF-IRI	n/a	n/a	n/a	LTF (NOTE 1)	n/a
	Option 2	MDF2	LTF	LTF	LTF	LTF	LTF

Table G.6-5 provides the scope of NF domain in the IMS that provides the IRI-POI/LTF for SMS over IMS when the target is a non-local ID with default IMS deployment option.

Table G.6-5: Scope of NF domain in IMS providing the LI functions for SMS over IMS (non-local ID) with Default

NFs with LI function	Non-roaming	Roaming with LBO		Roaming with HR
NFs with LI function	Non-roaming	VPLMN	HPLMN	VPLMN	HPLMN
P-CSCF	n/a	IRI-POI	n/a	n/a	n/a
S-CSCF	IRI-POI	n/a	IRI-POI	n/a	IRI-POI
LMISF-IRI	n/a	n/a	n/a	IRI-POI	n/a

Table G.6-6 provides the scope of NF domain in the IMS that provides the IRI-POI/LTF for SMS over IMS when the target is a non-local ID with Alternate IMS deployment option.

Table G.6-6: Scope of NF domain in IMS providing the LI functions for SMS over IMS (non-local ID) with Alternate option

NFs with LI function	Non-roaming	Roaming with LBO		Roaming with HR
NFs with LI function	Non-roaming	VPLMN	HPLMN	VPLMN	HPLMN
P-CSCF	IRI-POI	IRI-POI	n/a	n/a	IRI-POI
IBCF	n/a	n/a	IRI-POI	n/a	n/a
LMISF-IRI	n/a	n/a	n/a	IRI-POI	n/a

NOTE 1: Only for SMS over IMS not involving the emergency center.

NOTE 2: Only for SMS over IMS to emergency centers.

NOTE 3: The use of "n/a" in the above table implies that the LI function is not applicable to the NF for the indicated scenario.

NOTE 4: The LIPF is not aware of the above role played by the host NFs in providing the LI functions

NOTE 5: MDF2, MDF3 and LI-LCS Client which are also involved in providing the LI functions are not shown in the tables above.