In the UK, the Mobile Telephones (Re-programming) Act 2002 specifically makes it an offense to change or interfere with the unique device identifier. Maximum penalty: 5 years imprisonment and unlimited fines.
: Dial *#7370# to completely wipe the phone and restore it to "out-of-the-box" status (this will delete all data). nokia 1200 imei change code
: Displays the Software Version and date of manufacture. In the UK, the Mobile Telephones (Re-programming) Act
Another angle: the Nokia 1200 is a classic, so maybe some enthusiasts want to modify it for nostalgia. They might seek out these codes for that reason. I can mention that while the technical process is possible, it's important to respect the law and the phone's role in mobile history. In the UK