i want to identify my site visitor from the data that is sent on the headers.
i read that there's a header called HTTP_X_UP_SUBNO that gives kind of an id.
i followed the data that sent from users but few of them had data there (HTTP_X_UP_SUBNO).
my question, actualy few questions.
1. is this HTTP_X_UP_SUBNO belongs to the telephone or to the sim card?
2. is there any way to get this code for all users ?
3. is there any way to get data about the sim (like phone number)?

thanks all