Patent ID: 8660529

Claim:
A method for preventing illegitimate change of an identification number of a mobile terminal not having authentication information and a code, the method comprising: if change of an identification number is requested, receiving and storing new authentication information and encoding the new authentication information; determining whether a previously-stored first authentication information exists; if a previously-stored first authentication information does not exist, storing an identification number and the newly encoded authentication information as a first authentication information; and if a previously-stored first authentication information including a previously-stored identification number exists, performing the steps of determining whether the encoded authentication information corresponds to the first authentication information, if the encoded authentication information corresponds to the first authentication information, storing new identification number that replaces the previously stored identification number, and if the encoded authentication information does not correspond to the first authentication information, performing error handling; wherein the first authentication information is a number other than one or both of an equipment serial number (ESN) or an international mobile equipment identifier (IMEI) and is formed by encoding authentication information received from an authentication data server and is stored in a one-time programmable (OTP) area in the mobile terminal in which information stored once cannot be permanently changed or erased; and wherein both the previously-stored identification number and the new identification that replaces that previously stored identification number is stored in an area of a memory of the mobile terminal other than the OTP area.