First things first, *#6 isn't a real code. It's just an incomplete string that won't do a thing on any modern phone, iPhone or Android. The code you're probably thinking of is *#06# (don't forget the second hash). Punch that into your dialer, and the screen instantly pops up your phone's IMEI number—a unique 15-digit ID for your specific device-. Think of it as your phone's fingerprint. It's what carriers and manufacturers use to identify your hardware, check warranty status, or blacklist a phone if it's reported stolen. On iPhones, this is also the number you'd give Apple Support if you ever need a repair or replacement.

For those in Europe or the UK, the IMEI is just as critical. You'll need it when filing an insurance claim or dealing with your network provider about a lost device. Just open the Phone app, type *#06# exactly, and the number shows up automatically—no need to hit the call button. So, don't waste time on *#6; it leads nowhere. But *#06# is one of the few universal codes that actually gives you something useful in seconds.