03.333G security3GPPLawful InterceptionStage 2TS
Figure A7 shows the interception of unconditionally forwarded calls. The mobile that activated unconditional call forwarding (B) is the target for interception. In this case interception will be performed at the GMSC, where the SRI request for B is issued and subsequently the SRI response indicating that the call must be forwarded is received back.
Figure A7: Interception of unconditional call forwarding