A mobile telephone is provided with a look-up table enabling the mobile telephone to select preferred routes for connecting outgoing calls on the basis of predetermined codes which populate the look-up table. When operating in a cellular communications network a communications channel may thereby be selected from a plurality of available channels and ongoing transmission of an outgoing call may be routed via a further network selected in accordance with the route codes. The look-up table may be stored in a SIM card of the mobile telephone and may be updated via transmission of data from a remote control center via a cellular network or via a docking station to which the mobile telephone is releasably connectable. When the call is routed via a packet switching network, the routing code may include a string of network node addresses.