A cellular communication device has one or more access modes which allow reading and writing of data, for example to change its settings, for example passwords and even the entire operating system and also permitting access to personal information such as the user's telephone book. To prevent cloning and like illegal access activity, the device is configured by restricting access to such data access modes using a device unique security setting. The setting may be a password, preferably a one-time password, or it may be a unique or dynamic or one time configuration of the codes for the read and write instructions of the data mode. There is also disclosed a server, which manages the security settings such that data mode operates during an active connection between the device and the server, and a secure communication protocol for communicating between the server and the cellular device.