Section: 6.8.7.1 UMTS security context
Content: A UMTS security context in GSM BSS is only established for UMTS subscribers with a ME that is capable of UMTS AKA and connected to a R99+ VLR/SGSN. At the network side, two cases are distinguished: a) In case of an intersystem change to a UTRAN controlled by the same SGSN, the UMTS cipher/integrity keys CK and IK agreed during the latest UMTS AKA procedure are sent to the target RNC. b) In case of an intersystem change to a UTRAN controlled by another SGSN, the initial SGSN sends the UMTS cipher/integrity keys CK and IK agreed during the latest UMTS AKA procedure to the (new) SGSN controlling the target RNC. The new SGSN becomes the new anchor point for the service. The new SGSN then stores the UMTS cipher/integrity keys CK and IK and sends them to the target RNC. At the user side, in both cases, the ME applies the UMTS cipher/integrity keys CK and IK received from the USIM during the latest UMTS AKA procedure.