User equipment (UE) for determining an uplink ciphering activation time (UCAT) applicable to a communications channel on the UE, the communications channel compliant with a UMTS Terrestrial Radio Access Network (UTRAN), the UCAT usable to determine a time at which a new ciphering configuration for an uplink is to be implemented, the UE comprising:
- a processor configured to generate a response message after received a ciphering change request message, the response message configurable for sending on a radio bearer, the response message configured to include the UCAT, and, the response message having a size;
- where the processor is further configured to calculate the UCAT based on the determined size and a data rate, and, to include the calculated UCAT in the response message.