The following figures show the information flows for the invocation of Lawful Interception for Packet Data with multimedia. The figures show some of the basic signalling messages of the target Packet Data communication and the events on the X2 interfaces. The dotted lines indicate signalling depending on whether IRI information has been requested. The figures illustrate interception in the visited network.
The figures in this annex only apply to scenarios where the P-CSCF is located in the visited network. In some operator deployment scenarios, the P-CSCF will be in the Home Network. Where the P-CSCF is located in the Home Network and UE to P-CSCF signalling encryption is applied, all SIP messages between the P-CSCF and the UE will be encrypted within the visited network and therefore plain text interception in the visited network may not be possible.
Figures C.1.1 and C.1.2 show the intercept of the Multimedia registration for the case of visited network interception (refer to TS 23.228 clauses 188.8.131.52 and 184.108.40.206).
Figures C.1.1 and C.1.2 show the intercept of the Multimedia registration for the case of visited network interception, where the P-CSCF is located in the Visited Network (refer to TS 23.228 clauses 220.127.116.11 and 18.104.22.168).
Figure C.1.1: Intercept of Start of Multimedia Registration
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Figure C.1.2: Intercept of Continuation of Multimedia Registration