A method, system and computer readable medium for protecting a communications device connected to a communications system against an unauthorized intrusion, including providing a variable identifier to the communications device and entities authorized access thereto. The variable identifier is provided to a user address book and assigned with a permanent identifier and the permanent identifier, but not the variable identifier, is available to a user. The presence or absence of the correct variable identifier is sensed during an attempt to access the communications device for granting or denying access to the communications device. A new variable identifier is periodically provided to the communications device and to the authorized entities and to the user address book and assigned with the permanent identifier, wherein the permanent identifier, but not the new variable identifier, is available to the user.