FIELD: radio engineering, communication.
SUBSTANCE: invention relates to mobile communication. The invention is intended for detecting a single radio interface voice call continuity activation event indicating handover of user equipment between a packet switched domain and a circuit switched domain (4A); consistent with a serving radio network subsystem (4B) relocation procedure, suspending control plane signalling radio bearers; resetting the suspended signalling radio bearers (4C) and resuming the suspended signalling radio bearers in the domain handed over to, where resuming comprises protecting control plane signalling radio bearers of a domain handed over to using the same mapped security key that is used to encrypt user plane radio access bearers in the domain handed over to (4D).
EFFECT: facilitating handover between circuit switched and packet switched domains.
16 cl, 4 dwg
