Section: 6.8.6.2 GSM security context
Content: A GSM security context in UTRAN is only established for GSM subscribers. At the network side, two cases are distinguished: a) In case of an intersystem change to a GSM BSS controlled by the same SGSN, the SGSN starts to apply the 64-bit GSM cipher key Kc agreed during the latest GSM AKA procedure. b) In case of an intersystem change to a GSM BSS controlled by another SGSN, the initial SGSN sends the 64-bit GSM cipher key Kc agreed during the latest GSM AKA procedure to the (new) SGSN controlling the BSC. The new SGSN stores the key and applies it. The new SGSN becomes the new anchor point for the service. At the user side, in both cases, the ME applies the GSM cipher key Kc received from the SIM during the latest GSM AKA procedure.