Content for  TS 33.128  Word version:  18.6.0

For Phase-2 of HR LI, the following LI functions are provisioned over LI_X1 by the LIPF using the X1 protocol defined in ETSI TS 103 221-1 [7] with the LIPF playing the role of ADMF and the following LI functions playing the role of NE as per the reference model depicted in ETSI TS 103 221-1 [7].

• LMISF-IRI.
• MDF2.
• MDF3.

As described in clause 7.10.1, the Phase-2 of HR LI applies to inbound roaming target UEs that use IMS-based services with home-routed roaming or the inbound roaming UEs that use IMS-based services with home-routed roaming to communicate with the target non-local ID. The following target identities are used for Phase-2 of HR LI:

• IMPU.
• IMPI.
• PEIIMEI.
• IMEI.

The target identity in the IMPI format may contain a value derived from a SUPI or an IMSI. The target identity in the IMPU format containing a SIP URI or TEL URI may contain a value derived from a GPSI, MSISDN, an E.164 number, or IMSI. Only IMPU is used for target non-local ID. For triggered LALS, the LTF function associated with LMISF-IRI (see clause 7.3.1 and TR 33.928) is provisioned with the target identity of IMPU.

The LMISF-IRI shall be provisioned over LI_X1 by the LIPF for target based interception of IMS services in the VPLMN with home-routed roaming. The target identities listed in clause 7.10.4.2.1 shall apply for the provisioning of LMISF-IRI with LMISF-IRI playing the combined role of IRI-POI and CC-TF for the interception of IMS-based services in the VPLMN with home-routed roaming. The LMISF-IRI shall support the following service scoping from the structure defined in ETSI TS 103 221-1 [7]:

• The enumerated value of "voice" or "messaging" in the service type field.
• When location reporting is required, one or both of "reportBeginingAndEnd", "reportUponChange".
• "SuspendOnOutboundInternationalRoaming".

Table 7.10.4.2-1 shows the minimum details of the LI_X1 ActivateTask message used for provisioning the LMISF-IRI for Phase-2.

The MDF2 listed as the delivery endpoint over LI_X2 for xIRI generated by the LMISF-IRI shall be provisioned over LI_X1 by the LIPF. The target identities listed in clause 7.10.4.2.1 shall apply for the provisioning of MDF2. The MDF2 shall support the following service scoping from the structure defined in ETSI TS 103 221-1 [7]:

• The enumerated value of "voice" or "messaging" in the service type field.
• When location reporting is required, one or both of "reportBeginingAndEnd", "reportUponChange".

Table 7.10.4.2-2 shows the minimum details of the LI_X1 ActivateTask message used for provisioning the MDF2.

The MDF3 listed as the delivery endpoint over LI_X3 for xCC generated by the LMISF-CC shall be provisioned over LI_X1 by the LIPF. The target identities listed in clause 7.10.4.2.1 shall apply for the provisioning of MDF3. The MDF3 shall support the following service scoping from the structure defined in ETSI TS 103 221-1 [7]:

• The enumerated value of "voice" or "messaging" in the service type field.
• When location reporting is required, one or both of "reportBeginingAndEnd", "reportUponChange".

Table 7.10.4.2-4 shows the minimum details of the LI_X1 ActivateTask message used for provisioning the MDF3.

The LMISF-IRI extracts the SIP messages that it receives within the xCC from the BBIFF-U/BBIFF over the LI_X3_LITE_S. On the originating end of a voice session, the LMISF-IRI examines the SIP message, the stored LI_X2_LITE record and the stored LI_X3_LITE_S record to check for the following:

• Whether the calling party identity is a target.
• Whether the called party identity is a target non-local ID.

On the terminating end of a voice session, the LMISF-IRI examines the SIP message, the stored LI_X2_LITE record and the stored LI_X3_LITE_S record to check for the following:

• Whether the called party identity is a target.
• Whether the calling party identity is a target non-local ID.
• Whether the redirecting party identity is a target non-local ID.

The SIP headers used for identifying a calling party identity, called party identity, redirecting party identity can be same identities used by the IMS signaling functions with the following additions:

• P-Preferred Identity as calling party identity.

When any of the conditions listed above are true, the LMISF-IRI concludes that target is involved in an IMS session that shall be intercepted. Accordingly, the LMISF-IRI generates the xIRIs and delivers the same to the MDF2 over the LI_X2. For IMS-based voice services, if media interception is required, the LMISF-IRI sends a trigger for the same to the BBIFF-C/BBIFF over the LI_T1 interface.

The xIRIs generated at the LMISF-IRI shall be same as the xIRIs generated in the IRI-POIs present in the IMS signaling functions (see clause 7.12.4.12). As defined in TS 33.127 the LMISF-IRI generates the following xIRIs:

• Encapsulated SIP message.
• Start of interception with an established IMS session.

The xIRI CC Unavailable defined in TS 33.127 for IMS-based services is not applicable to N9HR LI and S8HR LI. The encapsulated SIP message is sent using the xIRI IMSMessage record. Further details of the xIRIs are defined in clause 7.12.4.12.

When the intercepted IMS-session requires the media interception, the LMISF-IRI sends a trigger to the BBIFF-C/BBIFF over to the LI_T1 interface (see TS 33.127) with LMISF-CC as the delivery end point. The LMISF-IRI upon discovering through the xIRIs received over the LI_X2_LITE interface that a change in SMF or SGW-C/SGW has occurred for an interception involving an IMS-session shall send the trigger to BBFF-C/BBIFF present in the new SMF or SGW-C/SGW over LI_T1 interface with LMISF-CC as the delivery end point to continue the IMS media interception when required. When the IMS session is completely released (e.g. all session-legs are released), the LMISF-IRI sends a trigger to the BBIFF-C/BBIFF to stop the media intereption. The LMISF-IRI may also send the trigger to stop the media interception when the target information is deprovisioned in the LMISF-IRI by the LIPF. The present document supports the media interception of IMS voice media.

The LI_T1 trigger that the LMISF-IRI sends to the BBIFF-C present in the SMF shall include at least the following information:

• The XID that LMISF-IRI receives from the LIPF over LI_X1 for the target related activation.
• Target identity: SUPI, PDU session ID, IMS voice media.
• Delivery end point: LMISF-CC.

The details of ActivateTask sent to the BBIFF-C in SMF over LI_T1 are shown in Table 7.10.4.4-1.

The DeactivateTask message that the LMISF-IRI sends to the BBIFF-C present in the SMF shall include the XID of the Task created by the ActivateTask message (see Table 7.10.4.4-1).

The LI_T1 trigger that the LMISF-IRI sends to the BBIFF-C present in the SGW-C/SGW shall include at least the following information:

• The XID that LMISF-IRI receives from the LIPF over LI_X1 for the target related activation.
• Target identity: IMSI, Bearer ID, IMS voice media.
• Delivery end point: LMISF-CC.

The details of ActivateTask sent to the BBIFF-C in SGW-C over LI_T1 are shown in Table 7.10.4.4-3.

The DeactivateTask message that the LMISF-IRI sends to the BBIFF-C/BBIFF present in the SGW-C/SGW shall include the XID of the Task created by the ActivateTask message (see Table 7.10.4.4-3).

When the trigger is received over the LI_T1 for activating the media interception, the BBIFF-C present in the SGW-C shall send a trigger over LI_T3 to the BBIFF-U present in the SGW-U when a dedicated bearer for the IMS media is established on the PDN connection. When the trigger is received over the LI_T1 for activating the media interception, the BBIFF-C present in the SMF shall send a trigger over LI_T3 to the BBIFF-U present in the UPF when the PDU session is modified for adding IMS media related QoS flow. If the trigger over LI_T1 is received for activating the media interception after the IMS media related changes has happened (i.e. dedicated bearer is established for IMS media, PDU session is modified for adding the IMS media related QoS flow), then the BBIFF-C shall send the trigger to the BBIFF-U over LI_T3 immediately. The BBIFF-C shall trigger the BBIFF-U to stop the delivery of xCC to the LMISF-CC when it receives the trigger from the LMISF-IRI over LI_T1 for stopping the media interception, independent of whether the IMS media related changes have happened or not.

The LI_T3 trigger that the BBIFF-C in SMF sends to the BBIFF-U present in the UPF shall include at least the following information:

• XID assigned locally by the BBIFF-C in the SMF.
• The ProductID that includes the XID it receives from the LMISF-IRI over LI_T1.
• Target identity: PFCP Session ID, PDR ID with the QFI associated with the IMS voice media (5Q = 1) related QoS flow.
• Delivery end point: LMISF-CC

The details of ActivateTask sent to the BBIFF-U in UPF over LI_T3 are shown in Table 7.10.4.5-1.

The DeactivateTask sent to the BBIFF-U present in the UPF over LI_T3 shall include the XID of the Task created by the ActivateTask message (see Table 7.10.4.5-1).

The LI_T3 trigger that the BBIFF-C in SGW-C sends to the BBIFF-U present in the SGW-U shall include at least the following information:

• XID assigned locally by the BBIFF-C in the SGW-C.
• The ProductID that includes the XID it receives from the LMISF-IRI over LI_T1.
• Target identity: PFCP Session ID, PDR ID with the F-TEID associated with the IMS voice media (QCI = 1) related dedicated bearer.
• Delivery end point: LMISF-CC.

The details of ActivateTask sent to the BBIFF-U in SGW-U over LI_T3 are shown in Table 7.10.4.5-2.

The DeactivateTask sent to the BBIFF-U present in the SGW-U over LI_T3 shall include the XID of the Task created by the ActivateTask message (see Table 7.10.4.5-2).