Patent ID: 6968378

Claim:
A processing unit connectable to a communications network, said processing unit comprising: a data carrier reader operable to read a network identity from a portable data carrier; a read/write register, wherein said processing unit is operable to write said network identity read from said portable data carrier into said read/write register; and a register flag operatively associated with said read/write register, wherein said processing unit is operable to set said register flag when said network identity is read from said portable data carrier; wherein said processing unit is operable to determine whether said register flag is set and to use said network identity for communicating via said communications network if said register flag is set, wherein if said register flag is not set said processing unit being operable to determine whether said portable data carrier is present in said data carrier reader, wherein if said portable data carrier is present in said data carrier reader said network identity is read from said portable data carrier for communicating via the communications network, said network identity is stored in said read/write register, and said register flag is set, wherein if said portable data carrier is absent from said data carrier reader said processing unit is operable to prevent access to the communications network.