can anyone help me with this question: if you go on a free wi-fi network (let's say in a cafe) does your iphone leave it's registration number, or are you complete anonymous? looking forward to your answer !
I have to agree with PapaST. Any time you connect to a network, your device name and MAC address (nothing to do with Apple) is recorded. In some cases, more information can be gathered, but generally just the device name and MAC address.
The only time you have to worry about what information is gathered is if you are doing something illegal, like hacking someone, or looking at child pornagraphy. Hopefully, you don't do either...
Unless you get someone else's phone to do whatever it is your going to do your phone is registered to you and can be traced right back to you regardless of the wi-fi connection.