respectively monitor base stations 70 71 node b through the iub interfaces in the example represented there is no iur interface between the two rncs involved 60 61 it will be noted that there could be such an iur interface but not serving for handover for example because the latter is between two different carrier frequencies in another embodiment the rncs 60 61 belong to different access networks a utran and a geran for example fig5 to 7 show active communication paths between the core network and ue 14 when the latter is moving in a typical hho scenario in the network configuration of fig4 initially fig5 a path is established in a conventional manner between the msc 30 of the core network and the ue 14 through the source rnc 60 and the base station 70 which depends thereon the srnc 60 and the ue each have a mac instance which for each dedicated logical channel in circuit mode and each direction of communication caters for the ciphering and deciphering functions in respect of the information transmitted over this first path in the manner indicated with reference to fig3 the static parameters ck bearer direction length of the module 20 and the initialization parameters of the counter 23.