Serial number query method, first set in your iphone-> General->; About this machine->; Serial number; (Find your serial number);
Then open the website, enter your serial number and click search.
The third-party software query method, the simplest, downloads an itools assistant software on the computer;
Open iTools and connect iPhone and PC with data cable;
The basic information of iPhone will appear in the main interface of iTools. Among them, the most important ones are the purchase date and the warranty expiration time. As for the activation date, it should refer to the time when you activated after the last brush.