Apparatus and method of ciphering in wireless telecommunications user equipment operative with a plurality of radio access networks

摘要

A method in a wireless telecommunications device operative with a plurality of radio access networks, the method comprising: when operating with a first radio access network reading at least one ciphering variable applicable in the second radio access network (e.g. in UMTS reading the value of a variable START from the USIM of the device). When at least one ciphering variable applicable in the second radio access network renders ciphering in the second radio access network infeasible without further authentication (e.g. in UMTS when the value of START in USIM is equal to a value THRESHOLD), using a substitute value for the ciphering parameter (e.g. START) when establishing a connection with the second radio access network.