Master the CHFI Challenge 2025: Crack the Code and Become a Cyber Sleuth!

The correct key combination to recover the IMEI number on a Nokia mobile phone is *#06#. This command is a standard GSM and mobile device USSD code that, when entered into the phone's dialer, prompts the device to display its International Mobile Equipment Identity (IMEI) number on the screen. The IMEI is a unique identifier used for mobile devices, often important for tracking and security purposes.

This command works on a variety of mobile phones, not just Nokia, making it widely recognized among users as the go-to method for retrieving the IMEI. This code is supported by most manufacturers ensuring a level of consistency across different devices.

In contrast, the other choices either do not exist as standard commands or are incorrectly formatted. For instance, #*06*# includes an incorrect sequence of characters, #06r seems to be a random character addition which does not relate to any known commands, and *1MEI# appears to be arbitrary. Therefore, the simplicity and universality of *#06# make it the correct answer.