In one embodiment, a method operable on a mobile communications device is disclosed, the method comprising generating an authentication key for securing a personalized indicium assigned to the mobile communications device, wherein the personalized indicium comprises a Personal Information Number (PIN) that is mapped to at least one identifier associated with the mobile communications device; transmitting a registration request to a network node operable with a wireless network, the registration request having a registration request payload including the authentication key; receiving a challenge message from the network node, the challenge message generated when the network node detects a change of the IP address associated with the mobile communications device, and responsive to receiving the challenge message, executing a challenge response including an authentication value of a challenge string transmitted in the challenge message, wherein the authentication value is created using the authentication key.